As filed with the Securities and Exchange Commission on July 12, 2019.

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

SEMGROUP CORPORATION

(Exact name of registrant as specified in its charter)

Two Warren Place

6120 S. Yale Avenue, Suite 1500

Tulsa, OK 74136-4231

(918) 524-8100

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Carlin G. Conner

President and Chief Executive Officer

Two Warren Place

6120 S. Yale Avenue, Suite 1500

Tulsa, OK 74136-4231

(918) 524-8100

(Name, address, including zip code, and telephone number, including area code, of agent for service)

WITH COPIES TO:

Robert J. Melgaard, Esq.

Jason B. Coutant, Esq.

Conner & Winters, LLP

4000 One Williams Center

Tulsa, Oklahoma 74172

(918) 586-5711

Approximate date of commencement of proposed sale to the public: From time to time after this Registration Statement becomes effective.

If the only securities being registered on this form are being offered pursuant to dividend or interest reinvestment plans, please check the following box.  ☐

If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.  ☒

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.  ☒

If this form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)B of the Securities Act.  ☐

CALCULATION OF REGISTRATION FEE

SEMGROUP CORPORATION

Senior Debt Securities

Subordinated Debt Securities

Class A Common Stock

Preferred Stock

Depositary Shares

Warrants

Purchase Contracts

Units

By this prospectus, we may offer and sell from time to time: senior debt securities, subordinated debt securities, Class A common stock, preferred stock, depositary shares, warrants, purchase contracts or units.

This prospectus provides you with a general description of the securities that may be offered. Each time we offer securities under this prospectus, we will provide you with one or more supplements to this prospectus that will contain additional information about the specific offering. The supplements may also add, update or change information contained in this prospectus. You should read this prospectus and any supplements to this prospectus carefully before you invest in the securities.    

Our Class A common stock is listed on the New York Stock Exchange under the symbol “SEMG.”

We may offer and sell these securities to or through one or more underwriters, dealers and agents, or directly to purchasers, on a continuous or delayed basis. The prospectus supplement for each offering of securities will describe in detail the plan of distribution.

There are significant risks associated with an investment in our securities. You should read carefully the risks we describe in the accompanying prospectus supplement as well as the risk factors discussed in our periodic reports that we file with the Securities and Exchange Commission, for a better understanding of the risks and uncertainties that investors in our securities should consider.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

This prospectus may not be used to sell securities unless accompanied by a prospectus supplement.

The date of this prospectus is July 12, 2019.

TABLE OF CONTENTS

You should rely only on the information contained in or specifically incorporated by reference into this prospectus and any prospectus supplement. We have not authorized anyone to provide you with information that is different. This prospectus and any prospectus supplement may only be used where it is legal to sell these securities. The information in this prospectus or any prospectus supplement or incorporated by reference into this prospectus or any prospectus supplement may only be accurate on the date of those documents.

Unless the context otherwise requires or as otherwise indicated, references in this prospectus to “SemGroup,” the “Company,” “we,” “us,” “our,” or similar terms refer to SemGroup^® Corporation, its consolidated subsidiaries and its predecessors. We sometimes refer to crude oil, natural gas, natural gas liquids (natural gas liquids, or “NGLs,” include ethane, propane, normal butane, iso-butane and natural gasoline), refined petroleum products and residual fuel oil, collectively, as “petroleum products.”

2

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (the “SEC”), utilizing a “shelf” registration process. Under this shelf process, we may, from time to time, sell any combination of the securities described in this prospectus in one or more offerings. For further information about our business and the securities, you should refer to the registration statement and its exhibits. The exhibits to the registration statement and the documents incorporated by reference in the registration statement contain the full text of the contracts and other important documents summarized in this prospectus. Since these summaries may not contain all the information that you may find important in deciding whether to purchase the securities that we may offer, you should review the full text of these documents. The registration statement can be obtained from the SEC as indicated under the heading “Where You Can Find More Information.”

This prospectus provides you with only a general description of the securities we may offer. Each time we offer to sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update, or change information contained in this prospectus. If there is any inconsistency between the information in this prospectus and any prospectus supplement, you should rely on the information in the prospectus supplement. You should read both this prospectus and any prospectus supplement together with the additional information described under the heading “Where You Can Find More Information.”

3

SEMGROUP CORPORATION

Our Business

We provide gathering, transportation, storage, distribution, marketing and other midstream services primarily to producers, refiners of petroleum products and other market participants located in the Gulf Coast, Midwest and Rocky Mountain regions of the United States of America (the “U.S.”) and Canada. We, or our significant equity method investee, have an asset base consisting of pipelines, gathering systems, storage facilities, terminals, processing plants and other distribution assets located in North American production and supply areas, including the Gulf Coast, Midwest, Rocky Mountain and Western Canadian regions. Our operations are conducted directly and indirectly through our primary operating segments.

Our Executive Offices

We are incorporated in Delaware and our executive offices are located at Two Warren Place, 6120 S. Yale Avenue, Suite 1500, Tulsa Oklahoma 74136-4231, and our telephone number is (918) 524-8100. Information contained on our website http://www.semgroupcorp.com, is not, and you must not consider such information to be, a part of this prospectus.

4

CAUTIONARY NOTICE REGARDING

FORWARD-LOOKING STATEMENTS

This prospectus, any accompanying prospectus supplement and the documents that we incorporate by reference herein or therein contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). We make these forward-looking statements in reliance on the safe harbor protections provided under the Private Securities Litigation Reform Act of 1995.

All statements, other than statements of historical facts, included or incorporated by reference in this prospectus and any accompanying prospectus supplement regarding the prospects of our industry, our anticipated financial performance, management’s plans and objectives for future operations, planned capital expenditures, business prospects, outcome of regulatory proceedings, market conditions and other matters, may constitute forward-looking statements. In addition, forward-looking statements generally can be identified by the use of forward-looking words such as “may,” “will,” “expect,” “intend,” “estimate,” “foresee,” “project,” “anticipate,” “believe,” “plans,” “forecasts,” “continue” or “could” or the negative of these terms or variations of them or similar terms. Although we believe that the expectations reflected in these forward-looking statements are reasonable, we cannot assure you that these expectations will prove to be correct. These forward-looking statements are subject to certain known and unknown risks, and uncertainties, as well as assumptions that could cause actual results to differ materially from those reflected in these forward-looking statements. Factors that could cause actual results to differ from those contemplated by our forward-looking statements include, but are not limited to, the following:

5

Consequently, all of the forward-looking statements made or incorporated by reference in this prospectus and any accompanying prospectus supplement are qualified by these cautionary statements and there can be no assurance that the actual results or developments we anticipate will be realized or, even if substantially realized, that they will have the consequences for, or effects on, our business or operations that we anticipate today. We assume no obligation to update publicly any such forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required by law.

6

USE OF PROCEEDS

Unless otherwise indicated in the applicable prospectus supplement, we intend to use the net proceeds from the sale of any securities described in this prospectus for working capital and general corporate purposes, which may include:

7

DESCRIPTION OF SENIOR DEBT SECURITIES

General

The following description applies to the senior debt securities offered by this prospectus. Unless otherwise indicated in the applicable prospectus supplement, the senior debt securities will be direct, unsecured obligations of SemGroup and will rank on a parity with all of our outstanding unsecured senior indebtedness. The senior debt securities may be issued in one or more series. The senior debt securities will be issued under an indenture between us and the trustee specified in the applicable prospectus supplement.

The statements under this caption are brief summaries of the provisions contained in the indenture, do not claim to be complete and are qualified in their entirety by reference to the indenture, a copy of which is filed as an exhibit to the registration statement of which this prospectus forms a part. Whenever defined terms are used but not defined in this prospectus, those terms have the meanings given to them in the indenture.

The following describes the general terms and provisions of the senior debt securities to which any prospectus supplement may relate. The particular terms of any senior debt security and the extent, if any, to which these general provisions may apply to the senior debt securities will be described in the prospectus supplement relating to the senior debt securities.

The indenture does not limit the aggregate principal amount of senior debt securities which may be issued under it. Rather, the indenture provides that senior debt securities of any series may be issued under it up to the aggregate principal amount which we may authorize from time to time. Senior debt securities may be denominated in any currency or currency unit we designate. The indenture does not limit or otherwise restrict the amount of other debt which we may incur or the other securities which we may issue.

Senior debt securities of a series may be issuable in registered form without coupons, which we refer to as “registered securities,” or in the form of one or more global securities in registered form, which we refer to as “global securities.”

You must review the prospectus supplement for a description of the following terms, where applicable, of each series of senior debt securities for which this prospectus is being delivered:

8

If any of the senior debt securities are sold for one or more foreign currencies or foreign currency units or if the principal of or any premium or interest on any series of senior debt securities is payable in one or more foreign currencies or foreign currency units, the restrictions, elections, tax consequences, specific terms and other information with respect to that issue of senior debt securities and those currencies or currency units will be described in the applicable prospectus supplement.

A judgment for money damages by courts in the U.S., including a money judgment based on an obligation expressed in a foreign currency, will ordinarily be rendered only in U.S. dollars. New York statutory law provides that a court shall render a judgment or decree in the foreign currency of the underlying obligation and that the judgment or decree shall be converted into U.S. dollars at the exchange rate prevailing on the date of entry of the judgment or decree.

Senior debt securities may be issued as original issue discount senior debt securities, to be sold at a substantial discount below their stated principal amount due at the stated maturity of the senior debt securities. There may be no periodic payments of interest on original issue discount securities. In the event of an acceleration of the maturity of any original issue discount security, the amount payable to the holder of the original issue discount security upon acceleration will be determined in accordance with the prospectus supplement, the terms of the security and the indenture, but will be an amount less than the amount payable at the maturity of the principal of the original issue discount security.

If the senior debt securities are issued with “original issue discount” within the meaning of the Internal Revenue Code of 1986, as amended, then a holder of those senior debt securities will be required under the Internal Revenue Code to include original issue discount in ordinary income for federal income tax purposes as it accrues, in accordance with a constant interest method that takes into account the compounding of interest, in advance of receipt of cash attributable to that income. Generally, the total amount of original issue discount on a

9

senior debt security will be the excess of the stated redemption price at maturity of the security over the price at which the security is sold to the public. To the extent a holder of a senior debt security receives a payment (at the time of acceleration of maturity, for example) that represents payment of original issue discount already included by the holder in ordinary income or reflected in the holder’s tax basis in the security, that holder generally will not be required to include the payment in income. The specific terms of any senior debt securities that are issued with original issue discount and the application of the original discount rules under the Internal Revenue Code to those securities will be described in a prospectus supplement for those securities.

Registration and Transfer

Unless otherwise indicated in the applicable prospectus supplement, senior debt securities will be issued only as registered securities. Senior debt securities issued as registered securities will not have interest coupons.

Registered securities (other than a global security) may be presented for transfer, with the form of transfer endorsed thereon duly executed, or exchanged for other senior debt securities of the same series at the office of the security registrar specified in the indenture. Transfer or exchange will be made without service charge, but we may require payment of any taxes or other governmental charges.

Book-Entry Senior Debt Securities

Senior debt securities of a series may be issued in whole or in part in the form of one or more global securities. Each global security will be deposited with, or on behalf of, a depositary identified in the applicable prospectus supplement. Global securities will be issued in registered form and in either temporary or permanent form. Until exchanged in whole or in part for the individual securities which it represents, a global security may not be transferred except as a whole by the depositary for the global security to a nominee of the depositary or by a nominee of the depositary to the depositary or another nominee of the depositary or by the depositary or any nominee to a successor depositary or any nominee of the successor. The specific terms of the depositary arrangement for a series of senior debt securities will be described in the applicable prospectus supplement.

Payment and Paying Agents

Unless otherwise indicated in an applicable prospectus supplement, payment of principal of and any premium and interest on registered securities will be made at the office of such paying agent or paying agents as we may designate from time to time. In addition, at our option, payment of any interest may be made by:

Unless otherwise indicated in an applicable prospectus supplement, payment of any installment of interest on registered securities will be made to the person in whose name the senior debt security is registered at the close of business on the regular record date for the payment.

Consolidation, Merger or Sale of Assets

The indenture relating to the senior debt securities provides that we may, without the consent of the holders of any of the senior debt securities outstanding under the indenture, consolidate with, merge into or transfer our assets substantially as an entirety to any person, provided that:

10

Any consolidation, merger or transfer of assets substantially as an entirety, which meets the conditions described above, would not create an event of default which would entitle holders of the senior debt securities, or the trustee acting on their behalf, to take any of the actions described below under “—Events of Default, Waivers, Etc.”

Leveraged and Other Transactions

The indenture and the senior debt securities do not contain provisions which would protect holders of the senior debt securities in the event we engaged in a highly leveraged or other transaction which could adversely affect the holders of senior debt securities.

Modification of the Indenture

The indenture provides that, with the consent of the holders of a majority in aggregate principal amount of the outstanding senior debt securities of each affected series, modifications and alterations of the indenture may be made which affect the rights of the holders of the senior debt securities. However, no modification or alteration may be made without the consent of the holder of each senior debt security affected which would, among other things,

Events of Default, Waivers, Etc.

An “event of default” with respect to senior debt securities of any series is defined in the indenture to include:

If an event of default with respect to any series of outstanding senior debt securities occurs and is continuing, either the trustee or the holders of not less than 25% in aggregate principal amount of the outstanding senior debt securities of that series may declare the principal amount (or with respect to original issue discount securities, the portion of the principal amount as may be specified in the terms of that series) of all senior debt securities of that series to be immediately due and payable. At any time after such a declaration of acceleration and before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in aggregate principal amount of the outstanding senior debt securities of any series may rescind and annul the declaration of acceleration and its consequences, but only if all events of default with respect to senior debt securities of such series have been remedied and all payments due, other than those due as a result of acceleration, have been made.

If an event of default occurs and is continuing, the trustee may, in its discretion, and at the written request to the trustee of holders of not less than 25% in aggregate principal amount of the outstanding senior debt securities

11

of any series and upon reasonable indemnity against the costs, expenses and liabilities to be incurred in compliance with such request and subject to certain other conditions set forth in the indenture will, proceed to protect the rights of the holders of all the senior debt securities of that series. Prior to acceleration of maturity of the outstanding senior debt securities of any series, the holders of not less than a majority in aggregate principal amount of the senior debt securities may, on behalf of all of the holders of the senior debt securities, waive any past default under the indenture except a default in the payment of principal of or any premium or interest on the senior debt securities of that series, a failure by us to convert any senior debt security into shares of our Class A common stock (to the extent such right is applicable) or in respect of a covenant or provision of the indenture which, pursuant to the indenture, cannot be waived without the consent of each holder of outstanding senior debt securities.

The indenture provides that upon the occurrence of an event of default specified in clauses (1) or (2) of the first paragraph in this subsection, we will, upon demand of the trustee, pay to it, for the benefit of the holders of any senior debt securities, the whole amount then due and payable on the affected senior debt securities for principal, premium, if any, and interest, if any. The indenture further provides that if we fail to pay such amount upon demand, the trustee may, among other things, institute a judicial proceeding for the collection of those amounts.

The indenture also provides that notwithstanding any of its other provisions, the holder of any senior debt security of any series will have the right to institute suit for the enforcement of any payment of principal of or any premium or interest on the senior debt securities when due and that such right will not be impaired without the consent of that holder.

We are required to file annually with the trustee a written statement of our officers as to the existence or non-existence of defaults under the indenture or the senior debt securities.

Satisfaction and Discharge

The indenture provides, among other things, that when all senior debt securities not previously delivered to the trustee for cancellation (1) have become due and payable or (2) will become due and payable at their stated maturity within one year, we may deposit with the trustee funds, in trust, for the purpose and in an amount sufficient to pay and discharge the entire indebtedness on the senior debt securities not previously delivered to the trustee for cancellation. Those funds will include all principal, premium, if any, and interest, if any, to the date of the deposit or to the stated maturity, as applicable. Upon such deposit, the indenture will cease to be of further effect except as to our obligations to pay all other sums due under the indenture and to provide the officers’ certificates and opinions of counsel required under the indenture. At such time we will be deemed to have satisfied and discharged the indenture.

Governing Law

The indenture and the senior debt securities will be governed by, and construed in accordance with, the laws of the State of New York.

Regarding the Trustee

Information concerning the trustee for a series of senior debt securities will be set forth in the prospectus supplement relating to that series of senior debt securities.

We may have normal banking relationships with the trustee in the ordinary course of business.

12

DESCRIPTION OF SUBORDINATED DEBT SECURITIES

General

The following description applies to the subordinated debt securities offered by this prospectus. Unless otherwise indicated in the applicable prospectus supplement, the subordinated debt securities will be unsecured, subordinated obligations of SemGroup. The subordinated debt securities may be issued in one or more series. The subordinated debt securities will be issued under an indenture between us and the trustee specified in the applicable prospectus supplement.

The statements under this caption are brief summaries of the provisions contained in the indenture, do not claim to be complete and are qualified in their entirety by reference to the indenture, a copy of which is filed as an exhibit to the registration statement of which this prospectus forms a part. Whenever defined terms are used but not defined in this prospectus, those terms have the meanings given to them in the indenture.

The following describes the general terms and provisions of the subordinated debt securities to which any prospectus supplement may relate. The particular terms of any subordinated debt security and the extent, if any, to which these general provisions may apply to the subordinated debt securities will be described in the prospectus supplement relating to the subordinated debt securities.

The indenture does not limit the aggregate principal amount of subordinated debt securities which may be issued under it. Rather, the indenture provides that subordinated debt securities of any series may be issued under it up to the aggregate principal amount which we may authorize from time to time. Subordinated debt securities may be denominated in any currency or currency unit we designate. The indenture does not limit or otherwise restrict the amount of other debt which we may incur or the other securities which we may issue.

Subordinated debt securities of a series may be issuable in the form of registered securities or global securities.

You must review the prospectus supplement for a description of the following terms, where applicable, of each series of subordinated debt securities for which this prospectus is being delivered:

13

If any of the subordinated debt securities are sold for one or more foreign currencies or foreign currency units or if the principal of or any premium or interest on any series of subordinated debt securities is payable in one or more foreign currencies or foreign currency units, the restrictions, elections, tax consequences, specific terms and other information with respect to that issue of subordinated debt securities and those currencies or currency units will be described in the applicable prospectus supplement.

A judgment for money damages by courts in the U.S., including a money judgment based on an obligation expressed in a foreign currency, will ordinarily be rendered only in U.S. dollars. New York statutory law provides that a court shall render a judgment or decree in the foreign currency of the underlying obligation and that the judgment or decree shall be converted into U.S. dollars at the exchange rate prevailing on the date of entry of the judgment or decree.

Subordinated debt securities may be issued as original issue discount securities, to be sold at a substantial discount below their stated principal amount due at the stated maturity of the subordinated debt securities. There may be no periodic payments of interest on original issue discount securities. In the event of an acceleration of the maturity of any original issue discount security, the amount payable to the holder of the original issue discount security upon acceleration will be determined in accordance with the prospectus supplement, the terms of the security and the indenture, but will be an amount less than the amount payable at the maturity of the principal of the original issue discount security.

If the subordinated debt securities are issued with “original issue discount” within the meaning of the Internal Revenue Code of 1986, as amended, then a holder of those subordinated debt securities will be required under the Internal Revenue Code to include original issue discount in ordinary income for federal income tax

14

purposes as it accrues, in accordance with a constant interest method that takes into account the compounding of interest, in advance of receipt of cash attributable to that income. Generally, the total amount of original issue discount on a subordinated debt security will be the excess of the stated redemption price at maturity of the security over the price at which the security is sold to the public. To the extent a holder of a subordinated debt security receives a payment (at the time of acceleration of maturity, for example) that represents payment of original issue discount already included by the holder in ordinary income or reflected in the holder’s tax basis in the security, that holder generally will not be required to include the payment in income. The specific terms of any subordinated debt securities that are issued with original issue discount and the application of the original discount rules under the Internal Revenue Code to those securities will be described in a prospectus supplement for those securities.

Registration and Transfer

Unless otherwise indicated in the applicable prospectus supplement, subordinated debt securities will be issued only as registered securities. Subordinated debt securities issued as registered securities will not have interest coupons.

Registered securities (other than a global security) may be presented for transfer, with the form of transfer endorsed thereon duly executed, or exchanged for other subordinated debt securities of the same series at the office of the security registrar specified in the indenture. Transfer or exchange will be made without service charge, but we may require payment of any taxes or other governmental charges.

Book-Entry Subordinated Debt Securities

Subordinated debt securities of a series may be issued in whole or in part in the form of one or more global securities. Each global security will be deposited with, or on behalf of, a depositary identified in the applicable prospectus supplement. Global securities will be issued in registered form and in either temporary or permanent form. Until exchanged in whole or in part for the individual securities which it represents, a global security may not be transferred except as a whole by the depositary for the global security to a nominee of the depositary or by a nominee of the depositary to the depositary or another nominee of the depositary or by the depositary or any nominee to a successor depositary or any nominee of the successor. The specific terms of the depositary arrangement for a series of subordinated debt securities will be described in the applicable prospectus supplement.

Payment and Paying Agents

Unless otherwise indicated in an applicable prospectus supplement, payment of principal of and any premium and interest on registered securities will be made at the office of such paying agent or paying agents as we may designate from time to time. In addition, at our option, payment of any interest may be made by:

Unless otherwise indicated in an applicable prospectus supplement, payment of any installment of interest on registered securities will be made to the person in whose name the subordinated debt security is registered at the close of business on the regular record date for the payment.

Subordination

The subordinated debt securities will be subordinated and junior in right of payment to some of our other indebtedness (which may include senior indebtedness for money borrowed) to the extent described in the applicable prospectus supplement.

15

Consolidation, Merger or Sale of Assets

The indenture relating to the subordinated debt securities provides that we may, without the consent of the holders of any of the subordinated debt securities outstanding under the indenture, consolidate with, merge into or transfer our assets substantially as an entirety to any person, provided that:

Any consolidation, merger or transfer of assets substantially as an entirety, which meets the conditions described above, would not create an event of default which would entitle holders of the subordinated debt securities, or the trustee acting on their behalf, to take any of the actions described below under “—Events of Default, Waivers, Etc.”

Leveraged and Other Transactions

The indenture and the subordinated debt securities do not contain provisions which would protect holders of the subordinated debt securities in the event we engaged in a highly leveraged or other transaction which could adversely affect the holders of subordinated debt securities.

Modification of the Indenture

The indenture provides that, with the consent of the holders of a majority in aggregate principal amount of the outstanding subordinated debt securities of each affected series, modifications and alterations of the indenture may be made which affect the rights of the holders of the subordinated debt securities. However, no modification or alteration may be made without the consent of the holder of each subordinated debt security affected which would, among other things,

Events of Default, Waivers, Etc.

An “event of default” with respect to subordinated debt securities of any series is defined in the indenture to include:

16

If an event of default with respect to any series of outstanding subordinated debt securities occurs and is continuing, either the trustee or the holders of not less than 25% in aggregate principal amount of the outstanding subordinated debt securities of that series may declare the principal amount (or with respect to original issue discount securities, the portion of the principal amount as may be specified in the terms of that series) of all subordinated debt securities of that series to be immediately due and payable. At any time after such a declaration of acceleration and before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in aggregate principal amount of the outstanding subordinated debt securities of any series may rescind and annul the declaration of acceleration and its consequences, but only if all events of default with respect to subordinated debt securities of such series have been remedied and all payments due, other than those due as a result of acceleration, have been made.

If an event of default occurs and is continuing, the trustee may, in its discretion, and at the written request to the trustee of holders of not less than 25% in aggregate principal amount of the outstanding subordinated debt securities of any series and upon reasonable indemnity against the costs, expenses and liabilities to be incurred in compliance with such request and subject to certain other conditions set forth in the indenture will, proceed to protect the rights of the holders of all the subordinated debt securities of that series. Prior to acceleration of maturity of the outstanding subordinated debt securities of any series, the holders of not less than a majority in aggregate principal amount of the subordinated debt securities may, on behalf of all of the holders of the subordinated debt securities, waive any past default under the indenture except a default in the payment of principal of or any premium or interest on the subordinated debt securities of that series, a failure by us on request to convert any subordinated debt security into shares of our Class A common stock (to the extent such right is applicable) or in respect of a covenant or provision of the indenture which, pursuant to the indenture, cannot be waived without the consent of each holder of outstanding subordinated debt securities.

The indenture provides that upon the occurrence of an event of default specified in clauses (1) or (2) of the first paragraph in this subsection, we will, upon demand of the trustee, pay to it, for the benefit of the holders of any subordinated debt securities, the whole amount then due and payable on the affected subordinated debt securities for principal, premium, if any, and interest, if any. The indenture further provides that if we fail to pay such amount upon demand, the trustee may, among other things, institute a judicial proceeding for the collection of those amounts.

The indenture also provides that notwithstanding any of its other provisions, the holder of any subordinated debt security of any series will have the right to institute suit for the enforcement of any payment of principal of or any premium or interest on the subordinated debt securities when due and that such right will not be impaired without the consent of that holder.

We are required to file annually with the trustee a written statement of our officers as to the existence or non-existence of defaults under the indenture or the subordinated debt securities.

Satisfaction and Discharge

The indenture provides, among other things, that when all subordinated debt securities not previously delivered to the trustee for cancellation (1) have become due and payable or (2) will become due and payable at their stated maturity within one year, we may deposit with the trustee funds, in trust, for the purpose and in an amount sufficient to pay and discharge the entire indebtedness on the subordinated debt securities not previously delivered to the trustee for cancellation. Those funds will include all principal, premium, if any, and interest, if any, to the date of the deposit or to the stated maturity, as applicable. Upon such deposit, the indenture will cease to be of further effect except as to our obligations to pay all other sums due under the indenture and to provide the officers’ certificates and opinions of counsel required under the indenture. At such time we will be deemed to have satisfied and discharged the indenture.

17

Governing Law

The indenture and the subordinated debt securities will be governed by, and construed in accordance with, the laws of the State of New York.

Regarding the Trustee

Information concerning the trustee for a series of subordinated debt securities will be set forth in the prospectus supplement relating to that series of subordinated debt securities.

We may have normal banking relationships with the trustee in the ordinary course of business.

18

DESCRIPTION OF CAPITAL STOCK

General

We have the authority to issue 194,000,000 shares of capital stock, which consist of 180,000,000 shares of Class A common stock, par value $0.01 per share (the “Class A common stock”), 10,000,000 shares of Class B common stock, par value $0.01 per share (the “Class B common stock,” together with the Class A common stock, the “Class A and Class B common stock”) and 4,000,000 shares of preferred stock, par value $0.01 per share (the “Preferred Stock”).

Common Stock

As of June 30, 2019, 79,582,304 shares of our Class A common stock were issued and outstanding and no shares of our Class B common stock were issued and outstanding. All of the outstanding shares of our Class A common stock are fully paid and nonassessable.

The Class A common stock and the Class B common stock are identical in all respects, except that the Class B common stock is not eligible for trading on a national securities exchange or market system.

Voting Rights

Holders of shares of Class A and Class B common stock are entitled to one vote per share on each matter on which the holders of our common stock are entitled to vote, including the election of directors. Except as otherwise required by law, holders of Class A and Class B common stock vote together as a single class. Holders of Class A and Class B common stock do not have cumulative voting rights with respect to the election of directors, meaning that the holders of a majority of the shares voting for the election of directors can elect all of the directors standing for election.

Dividend and Liquidation Rights

Subject to the rights of any then-outstanding shares of Preferred Stock, the holders of Class A and Class B common stock are entitled to receive, equally and ratably, share for share, such dividends as may be declared by our Board of Directors from funds legally available. The terms of our current revolving credit facility, however, restrict, to some extent, the payment of cash dividends on our common stock. In the event of a liquidation, dissolution, distribution of assets or other winding up of our company, the holders of the Class A and Class B common stock are entitled to share equally and ratably, share for share, in all assets remaining for distribution to stockholders, subject to any preferential liquidation rights of any Preferred Stock that at the time may be outstanding.

No Redemption or Preemptive Rights

Holders of Class A and Class B common stock have no redemption or preemptive rights. There are no sinking fund provisions applicable to our Class A and Class B common stock.

Conversion Rights of Class B Common Stock

Each share of Class B common stock is convertible at any time at the option of the holder thereof into one share of Class A common stock. We will reserve and keep available out of our authorized but unissued Class A common stock at least the number of shares of Class A common stock that would become issuable upon the conversion of all shares of Class B common stock at any time outstanding.

Transfer Agent

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A.

19

Registration Rights

On July 17, 2017, we completed our acquisition of 100% of the equity interests in Buffalo Parent Gulf Coast Terminals LLC, the parent company of Buffalo Gulf Coast Terminals LLC and HFOTCO LLC doing business as Houston Fuel Oil Terminal Company, from Buffalo Investor I, L.P. and Buffalo Investor II, L.P. (collectively, the “Sellers”). We refer to this acquisition as the “HFOTCO Acquisition.” Consideration for the HFOTCO Acquisition included the issuance of 12,383,900 shares of our Class A common stock to the Sellers. In connection with the issuance of the Class A common stock, we entered into a registration rights agreement with the Sellers pursuant to which we are required to prepare and file a registration statement to permit the resale of such shares of Class A common stock held by the Sellers from time to time as permitted by Rule 415 under the Securities Act. We have registered such shares of Class A common stock on a registration statement on Form S-3 pursuant to this registration rights agreement. We must use our reasonable best efforts to keep such registration statement continuously effective under the Securities Act until the earlier of (i) the date when all of the registrable securities covered by such registration statement have been sold and (ii) there are no longer any registrable securities outstanding. In certain circumstances, the Sellers may elect to sell shares under such registration statement in an underwritten public offering. In addition, the registration rights agreement provides the Sellers with certain piggyback registration rights, pursuant to which the Sellers may elect to participate in an underwritten public offering of our Class A common stock initiated by us.

Preferred Stock

As of June 30, 2019, there were 350,000 shares of our Series A Cumulative Perpetual Convertible Preferred Stock issued and outstanding and no other shares of Preferred Stock were issued and outstanding. Our Board of Directors may, without further approval of the stockholders, issue Preferred Stock from time to time in one or more series and fix the dividend rates and terms, conversion rights, voting rights, redemption rights and terms, liquidation preferences, sinking fund and any other rights, preferences, privileges and restrictions applicable to each series of Preferred Stock.

The specific matters that the Board of Directors may determine include the following:

The purpose of authorizing the Board of Directors to determine these rights, preferences, privileges and restrictions is to eliminate delays associated with a stockholder vote on specific issuances. The Board of Directors intends for the Preferred Stock to be used for capital raising, financing and acquisition needs or opportunities. The Board of Directors does not intend to use the Preferred Stock for any defensive or anti-takeover purposes or for the purpose of implementing any stockholder rights plan.

Series A Cumulative Perpetual Convertible Preferred Stock

On January 19, 2018 (the “Issue Date”), we sold to certain institutional investors, in a private placement, an aggregate of 350,000 shares of our Series A Cumulative Perpetual Convertible Preferred Stock (the “Series A

20

Preferred Stock”) convertible into 10,606,061 shares (subject to adjustment) of our Class A common stock, for a cash purchase price of $1,000 per share of Series A Preferred Stock and aggregate gross proceeds to us of $350,000,000. These proceeds were utilized to repay amounts borrowed under our revolving credit facility, to fund growth capital expenditures and for general corporate purposes.

Dividend Payments

The shares of Series A Preferred Stock (the “Preferred Shares”) are a class of equity security that ranks senior to the Class A common stock with respect to distribution rights and rights upon liquidation. Subject to certain exceptions, so long as any Preferred Shares remain outstanding, no dividend or distribution will be declared or paid on, and no redemption or repurchase will be agreed to or consummated of, stock on a parity with the Preferred Shares (“Parity Stock”), Class A common stock or any other shares of stock junior to the Preferred Shares, unless all accumulated and unpaid dividends for all preceding full fiscal quarters have been declared and paid with respect to the Preferred Shares. In addition, no dividend or distribution or redemption or repurchase shall be paid on Parity Stock, Class A common stock or any other shares of stock junior to the Preferred Shares for any period unless the Series A Preferred Stock has been paid full cash dividends in respect of the same period; provided, however, that we may pay dividends on Class A common stock in respect of any fiscal quarter ending on or prior to June 30, 2020 (the “PIK Period”).

PIK Dividends

The holders of Preferred Shares (the “Holders”) will receive quarterly distributions equal to an annual rate of 7.0% ($70.00 per share annualized) of $1,000 per Preferred Share, subject to certain adjustments (the “Liquidation Preference”). With respect to any quarter ending on or prior to the PIK Period, we may elect, in lieu of paying a distribution in cash, to have the amount that would have been payable if such dividend had been paid in cash added to the Liquidation Preference. We have made such an election with respect to each of our quarterly distributions since the Issue Date which has increased the Liquidation Preference such that as of June 30, 2019, the Preferred Shares are convertible into 11,726,913 shares of our Class A common stock.

Holder Conversion

Beginning July 19, 2019, the eighteen month anniversary of the Issue Date, the Holders may convert their Preferred Shares into a number of shares of Class A common stock equal to, per Preferred Share, the quotient of the Liquidation Preference divided by $33.00 (the “Conversion Price”), subject to certain adjustments including customary anti-dilution adjustments (such quotient, the “Conversion Rate”). Holders may elect to convert the Preferred Shares, in whole or in part, so long as the aggregate value of Class A common stock to be issued pursuant to such partial conversion is not for less than $50,000,000 or a lesser amount if such conversion relates to all of a Holder’s remaining Preferred Shares.

Company Conversion

On or after the three year anniversary of the Issue Date, if the Holders have not elected to convert all of their Preferred Shares, we may cause the outstanding Preferred Shares to be converted into a number of shares of Class A common stock equal to, per Preferred Share, the quotient of the Liquidation Preference divided by the Conversion Price, subject to certain adjustments including customary anti-dilution adjustments; provided, that in order for us to exercise such conversion right, (w) the closing sale price of the Class A common stock during a designated period be greater than or equal to $47.85, (x) the resale of the shares of Class A common stock issuable upon conversion shall be registered and available for resale by the Holders pursuant to a registration statement declared effective by the SEC covering such resales, (y) the Class A common stock is listed on a national securities exchange, and (z) certain average daily trading volume minimum requirements are met. We may elect to convert the Preferred Shares, in whole or in part, so long as the aggregate value of Class A common stock to be issued pursuant to such partial conversion is not for less than $50,000,000 or such lesser amount if such conversion relates to the aggregate amount of all remaining Preferred Shares.

21

Change of Control

Upon a change of control that involves consideration that is at least 90% cash, Holders are required to convert their Preferred Shares into Class A common stock at a rate equal to the greater of (i) the product of the Conversion Rate and the quotient of (a) the product of the Conversion Price and the Cash Change of Control Conversion Premium (as defined below), divided by (b) the average volume weighted average price of the Class A common stock during a designated period and (ii) the Conversion Rate otherwise in effect at such time. The “Cash Change of Control Conversion Premium” equals

Upon a change of control that involves consideration that is less than 90% cash, Holders may elect to:

Voting Rights

Holders shall be entitled to vote on all matters on which the holders of shares of Class A common stock are entitled to vote and, except as otherwise provided in our Certificate of Incorporation, or by law, the Holders shall vote together with the holders of shares of Class A common stock as a single class. Each Holder shall be entitled to a number of votes equal to the number of votes such Holder would have had if all Preferred Shares held by such Holder had been converted into shares of Class A common stock.

So long as any Preferred Shares are outstanding, the affirmative vote or consent of the Holders of at least 66²⁄₃% of the outstanding Preferred Shares, voting together as a separate class, will be necessary for effecting or validating:

22

However, the foregoing rights of the Holders will not restrict any of the following actions, subject to certain terms:

Notwithstanding the vote or consent of the Holders described above, after the Issue Date, we may issue certain amounts of Parity Stock without the approval of the Holders if: (A) the aggregate amount of such issuances is less than or equal to $250,000,000 (excluding the aggregate amount of any additional Preferred Shares issued to WP SemGroup Holdings, L.P. (“Warburg”)); or (B) the aggregate initial purchase price of the then outstanding Preferred Shares is less than $100,000,000.

Transfer Restrictions

Prior to the first anniversary of the Issue Date, no Holder may transfer any Preferred Shares, other than to an affiliate, without our prior written consent. Prior to the second anniversary of the Issue Date, Holders and their affiliates are prohibited from directly or indirectly engaging in any short sales or other hedging transactions involving the Preferred Shares and Class A common stock underlying such Holder’s Preferred Shares.

Preemptive Rights

For so long as Warburg and its affiliates collectively own 75% or more of the outstanding Preferred Shares acquired by Warburg and its affiliates on the Issue Date, we, prior to any issuance of Parity Stock, are required to provide Warburg with a reasonable opportunity to purchase all or any portion of such shares of Parity Stock to be issued by us on substantially the same terms offered to the other purchasers of such securities.

Board Observer Rights

We have granted to Warburg, until Warburg no longer owns at least 50% of the Preferred Shares issued to Warburg and its affiliates on the Issue Date, certain rights to designate an observer (the “Board Observer”) to our Board of Directors, who shall have the right to attend full meetings of the Board of Directors (including any executive session and certain committees thereof) and receive such materials as other members of the Board of Directors receive.

Registration Rights

We have granted Warburg and its affiliates rights to require us to file and maintain, subject to certain penalties, registration statements with respect to the resale of the Class A common stock issuable upon conversion of the Preferred Shares. We are required to file or cause to be filed a registration statement (the “Preferred Registration Statement”) for the resale of registrable securities held by Warburg and the resale of the Class A common stock issuable upon conversion of the Preferred Shares held by Holders other than Warburg. We are required to cause the Preferred Registration Statement to become effective no later than the eighteen-month anniversary of the Issue Date. In certain circumstances, Warburg and its affiliates will have piggyback

23

registration rights on offerings initiated by us or other persons who have been granted registration rights, and Warburg has the right to request two underwritten offerings upon certain terms and conditions. Holders of registrable securities will cease to have registration rights on the earlier of (i) the second anniversary of the date on which Preferred Shares are first converted into shares of Class A common stock and (ii) the date on which no registrable securities remain outstanding; provided, that we shall use reasonable best efforts to maintain the effectiveness of the Preferred Registration Statement during all periods in which Warburg (A) is deemed to be an affiliate of the Company pursuant to Rule 144 under the Securities Act or (B) together with its affiliates, owns more than 5% of the Class A common stock (including Class A common stock it would own on an as-converted basis).

Depositary Shares

We may issue fractional shares of Preferred Stock rather than full shares of Preferred Stock. If we exercise this option, we will issue receipts for depositary shares, and each of these depositary shares will represent a fraction (to be set forth in the prospectus supplement relating to such depositary shares) of a share of a particular series of Preferred Stock.

The shares of any series of Preferred Stock underlying the depositary shares will be deposited under a deposit agreement between us and a bank or trust company selected by us. The depositary will have its principal office in the United States and a combined capital and surplus of at least $50,000,000. Subject to the terms of the deposit agreement, each owner of a depositary share will be entitled, in proportion to the applicable fraction of a share of Preferred Stock underlying the depositary share, to all of the rights and preferences of the Preferred Stock underlying that depositary share. Those rights may include dividend, voting, redemption, conversion and liquidation rights.

The depositary shares will be evidenced by depositary receipts issued under a deposit agreement. Depositary receipts will be distributed to those persons purchasing the fractional shares of Preferred Stock underlying the depositary shares, in accordance with the terms of the offering. We will describe the material terms of the deposit agreement, the depositary shares and the depositary receipts in a prospectus supplement relating to the depositary shares. You should also refer to the forms of the deposit agreement and depositary receipts that will be filed with the SEC in connection with the offering of the specific depositary shares.

Anti-Takeover Provisions

Provisions of the General Corporation Law of the State of Delaware (the “DGCL”) and of our amended and restated certificate of incorporation and amended and restated bylaws may delay, defer, make more difficult or prevent a change of control of our company.

Delaware Business Combination Statute

We are subject to Section 203 of the DGCL. In general, Section 203 prohibits a “business combination” between a corporation and an “interested stockholder” within three years of the time the stockholder became an interested stockholder, unless:

24

Generally, a “business combination” includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. Generally, an “interested stockholder” is a person who owns, individually or with or through other persons, 15% or more of the corporation’s outstanding voting stock. Our Board of Directors could rely on this provision of the DGCL to prevent or delay an acquisition of us.

Certificate of Incorporation and Bylaws

Issuance of Common Stock. The authorized but unissued shares of our common stock are available for future issuance without stockholder approval, unless required by our amended and restated certificate of incorporation or amended and restated bylaws, by the rules of the New York Stock Exchange (on which our Class A common stock is listed), or by applicable law. These additional shares may be used for a variety of corporate purposes, including future public offerings to raise additional capital, corporate acquisitions and employee benefit plans. The existence of authorized but unissued and unreserved common stock could also render more difficult or discourage an attempt to obtain control of us by means of a proxy contest, tender offer, merger or otherwise.

Advance Notice Procedures. Our amended and restated bylaws provide that proposals and director nominations made by a stockholder to be voted upon at any annual meeting or special meeting of stockholders may be taken only if such proposal or director nomination is “properly brought” before such meeting. In order for any matter to be considered “properly brought” before an annual meeting or a special meeting, a stockholder must comply with certain requirements regarding advance notice to the company. The advance notice provisions could have the effect of delaying, until the next stockholders meeting, stockholder actions which are favored by the holders of a majority of our outstanding voting stock.

Special Meetings of Stockholders. Stockholders do not have the right to call special meetings of stockholders. Only the Chairman of our Board of Directors, our Chief Executive Officer or a majority of the Board of Directors may call a special meeting of stockholders. The only business that may be conducted at a special meeting of stockholders is the business properly brought before the meeting pursuant to our notice of meeting. This provision will make it more difficult for stockholders to take action opposed by the Board of Directors.

Exclusive Forum

Our amended and restated bylaws provide that unless SemGroup consents in writing to the selection of an alternative forum, to the fullest extent permitted by law, and subject to applicable jurisdictional requirements, the sole and exclusive forum for any stockholder (including any beneficial owner) of SemGroup to bring internal corporate claims (as defined below) will be a state court located within the State of Delaware (or, if no state court located within the State of Delaware has jurisdiction, the federal district court for the District of Delaware). “Internal corporate claims” means claims, including claims in the right of SemGroup, (i) that are based upon a violation of a duty by a current or former director, officer, employee or stockholder in such capacity or (ii) as to which the DGCL confers jurisdiction upon the Court of Chancery of the State of Delaware. This bylaw is referred to herein as the “exclusive forum bylaw.”

Our amended and restated bylaws further provide that if any action the subject matter of which is within the exclusive forum bylaw is brought outside the State of Delaware, the stockholder bringing the action will be deemed to have consented to (i) the personal jurisdiction of the state and federal courts located within the State of Delaware in connection with any action brought by SemGroup in any such court to enforce the exclusive forum bylaw and (ii) having service of process made upon such stockholder in any such action by service upon such stockholder’s counsel in the action brought outside the State of Delaware as agent for such stockholder.

25

DESCRIPTION OF WARRANTS

Offered Warrants

We may issue warrants that are debt warrants or equity warrants. We may offer warrants separately or together with one or more additional warrants or debt or equity securities or any combination of those securities in the form of units, as described in the applicable prospectus supplement. If we issue warrants as part of a unit, the accompanying prospectus supplement will specify whether those warrants may be separated from the other securities in the unit prior to the warrants’ expiration date.

Debt Warrants

We may issue, together with debt securities or separately, warrants for the purchase of debt securities on terms to be determined at the time of sale.

Equity Warrants

We may also issue, together with equity securities or separately, warrants to purchase, including warrant spreads, shares of our Class A common stock on terms to be determined at the time of sale.

General Terms of Warrants

The applicable prospectus supplement will contain, where applicable, the following terms of and other information relating to the warrants and warrant spreads:

26

Significant Provisions of the Warrant Agreements

We will issue the warrants under one or more warrant agreements to be entered into between us and a bank or trust company, as warrant agent, in one or more series, which will be described in the prospectus supplement for the warrants. The following summaries of significant provisions of the warrant agreements and the warrants are not intended to be comprehensive, and holders of warrants should review the detailed description of the relevant warrant agreement included in any prospectus supplement.

Modifications Without Consent of Warrantholders

We and the warrant agent may amend the terms of the warrants and the warrant certificates without the consent of the holders to:

Enforceability of Rights of Warrantholders

The warrant agents will act solely as our agents in connection with the warrant certificates and will not assume any obligation or relationship of agency or trust for or with any holders of warrant certificates or beneficial owners of warrants. Any holder of warrant certificates and any beneficial owner of warrants may, without the consent of any other person, enforce by appropriate legal action, on its own behalf, its right to exercise the warrants evidenced by the warrant certificates in the manner provided for in that series of warrants or pursuant to the applicable warrant agreement. No holder of any warrant certificate or beneficial owner of any warrants will be entitled to any of the rights of a holder of the debt securities or any other warrant property, if any, purchasable upon exercise of the warrants, including, without limitation, the right to receive the payments on those debt securities or other warrant property or to enforce any of the covenants or rights in the relevant indenture or any other similar agreement.

Registration and Transfer of Warrants

Subject to the terms of the applicable warrant agreement, warrants in registered, definitive form may be presented for exchange and for registration of transfer at the corporate trust office of the warrant agent for that series of warrants, or at any other office indicated in the prospectus supplement relating to that series of warrants, without service charge. However, the holder will be required to pay any taxes and other governmental charges as described in the warrant agreement. The transfer or exchange will be effected only if the warrant agent for the series of warrants is satisfied with the documents of title and identity of the person making the request.

New York Law to Govern

The warrants and each warrant agreement will be governed by, and construed in accordance with, the laws of the State of New York.

27

DESCRIPTION OF PURCHASE CONTRACTS

We may issue purchase contracts, including contracts obligating holders to purchase from us and us to sell to the holders, a specified principal amount of debt securities or a specified number of shares of Class A common stock or Preferred Stock or any of the other securities that we may sell under this prospectus (or a range of principal amount or number of shares pursuant to a predetermined formula) at a future date or dates. The consideration payable upon settlement of the purchase contracts may be fixed at the time the purchase contracts are issued or may be determined by a specific reference to a formula set forth in the purchase contracts. The purchase contracts may be issued separately or as part of units consisting of a purchase contract and other securities or obligations issued by us or third parties, including United States treasury securities, securing the holders’ obligations to purchase the relevant securities under the purchase contracts. The purchase contracts may require us to make periodic payments to the holders of the purchase contracts or units or vice versa, and the payments may be unsecured or prefunded on some basis. The purchase contracts may require holders to secure their obligations under the purchase contracts in a specified manner and in some circumstances we may deliver newly issued prepaid purchase contracts, often referred to as “prepaid securities,” upon release to a holder of any collateral securing such holder’s obligations under the original purchase contract.

The applicable prospectus supplement will describe the terms of any purchase contracts or purchase units and, if applicable, such other securities or obligations. The description in the prospectus supplement will not necessarily be complete and will be qualified in its entirety by reference to the purchase contracts, and, if applicable, collateral arrangements, relating to the purchase contracts.

28

DESCRIPTION OF UNITS

We may issue units consisting of one or more purchase contracts, warrants, debt securities, shares of Preferred Stock, depositary shares, shares of Class A common stock or any combination of such securities. The applicable prospectus supplement will describe:

PLAN OF DISTRIBUTION

From time to time, we may sell the securities offered by this prospectus:

This prospectus may be used in connection with any offering of our securities through any of these methods or other methods described in the applicable prospectus supplement. Any underwriter, dealer or agent may be deemed to be an “underwriter” within the meaning of the Securities Act.

The applicable prospectus supplement relating to the securities will set forth:

If underwriters or dealers are used in the sale, the securities will be acquired by the underwriters or dealers for their own account and may be resold from time to time in one or more transactions,

The securities may be offered to the public either through underwriting syndicates represented by one or more managing underwriters or directly by one or more of such firms. Unless otherwise set forth in the applicable prospectus supplement, the obligations of underwriters or dealers to purchase the offered securities will be

29

subject to certain conditions precedent, and the underwriters or dealers will be obligated to purchase all the offered securities if any are purchased. Any public offering price and any discounts or concessions allowed or reallowed or paid by underwriters or dealers to other dealers may be changed from time to time.

Securities may be sold directly by us or through agents designated by us from time to time. Any agent involved in the offer or sale of the securities in respect of which this prospectus is delivered will be named, and any commissions payable by us to the agent will be set forth, in the applicable prospectus supplement. Unless otherwise indicated in the applicable prospectus supplement, any such agent will be acting on a best efforts basis for the period of its appointment.

If so indicated in the applicable prospectus supplement, we will authorize underwriters, dealers or agents to solicit offers from certain specified institutions to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. Such contracts will be subject to any conditions set forth in the applicable prospectus supplement and the prospectus supplement will set forth the commission payable for solicitation of such contracts. The underwriters and other persons soliciting such contracts will have no responsibility for the validity or performance of any such contracts.

Underwriters, dealers and agents may be entitled under agreements entered into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution by us to payments which they may be required to make. Underwriters, dealers and agents may be customers of, engage in transactions with, or perform services for, us in the ordinary course of business.

Each class or series of securities will be a new issue of securities with no established trading market, other than our Class A common stock, which is listed on the New York Stock Exchange. We may elect to list any other class or series of securities on any exchange, but are not obligated to do so. Any underwriters to whom securities are sold by us for public offering and sale may make a market in such securities, but such underwriters will not be obligated to do so and may discontinue any market making at any time without notice. No assurance can be given as to the liquidity of the trading market for any securities.

30

LEGAL MATTERS

The validity of the securities offered by this prospectus will be passed upon by Conner & Winters, LLP, Tulsa, Oklahoma. Certain other legal matters will be passed upon for us by Conner & Winters, LLP, Tulsa, Oklahoma, and for the underwriters, dealers, or agents, if any, by their own legal counsel. As of the date of this prospectus, attorneys at Conner & Winters, LLP owned 59,127 shares of our Class A common stock.

EXPERTS

The audited consolidated financial statements of SemGroup Corporation and subsidiaries as of December 31, 2018 and 2017 and for each of the two years in the period ended December 31, 2018 and the effects of the adjustments to the 2016 consolidated financial statements to retrospectively apply the change in reportable operating segments as described in Note 21 and management’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2018, incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the reports of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing.

The consolidated financial statements of SemGroup Corporation for the year ended December 31, 2016 (before the effects of the adjustments to retrospectively apply the change in reportable operating segments as described in Note 21) incorporated by reference in this prospectus have been so incorporated by reference in reliance upon the report of BDO USA, LLP, an independent registered public accounting firm, incorporated herein by reference, given on the authority of said firm as experts in auditing and accounting.

The financial statements of White Cliffs Pipeline, L.L.C. as of December 31, 2018 and 2017 and for each of the two years in the period ended December 31, 2018, incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the report of Grant Thornton LLP, independent certified public accountants, upon the authority of said firm as experts in accounting and auditing.

The financial statements of White Cliffs Pipeline, L.L.C. for the year ended December 31, 2016 incorporated by reference in this prospectus have been so incorporated in reliance upon the report of BDO USA, LLP, an independent auditor, incorporated herein by reference, given on the authority of said firm as experts in auditing and accounting.

31

WHERE YOU CAN FIND MORE INFORMATION

This prospectus constitutes a part of a registration statement on Form S-3 (together with all amendments, supplements, schedules and exhibits to the registration statement, referred to as the registration statement) that we have filed with the SEC under the Securities Act with respect to the securities offered by this prospectus. This prospectus does not contain all the information which is in the registration statement. Certain parts of the registration statement are omitted as allowed by the rules and regulations of the SEC. We refer you to the registration statement for further information about our company and the securities offered by this prospectus. Statements contained in this prospectus concerning the provisions of documents are not necessarily complete, and each statement is qualified in its entirety by reference to the copy of the applicable document filed with the SEC.

We also file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC also maintains an Internet website which provides online access to reports, proxy and information statements and other information regarding companies that file electronically with the SEC at the address http://www.sec.gov.

32

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” into this prospectus the information we file with them, which means we can disclose important business and financial information about us to you by referring you to those documents. The information incorporated by reference is considered to be a part of this prospectus, except for any information that is superseded by information included directly in this prospectus and any prospectus supplement.

We incorporate by reference the documents listed below that we previously filed with the SEC (SEC File No. 1-34736) and any future filings made with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act (other than any portions of such filings that are furnished rather than filed under applicable SEC rules) prior to the completion of the offering covered by this prospectus:

These filings have not been included in or delivered with this prospectus. We will provide to each person, including any beneficial owner to whom this prospectus is delivered, a copy of any or all information that has been incorporated by reference in this prospectus but not delivered with this prospectus. You can access these documents on our website at http://www.semgroupcorp.com or you may request a copy of these filings at no cost, by writing or telephoning us at the following address:

SemGroup Corporation

Two Warren Place

6120 S. Yale Avenue, Suite 1500

Tulsa, Oklahoma 74136-4231

Attention: Investor Relations

(918) 524-8100

Except as otherwise specifically incorporated by reference in this prospectus, information contained in, or accessible through, our website is not a part of this prospectus.

33

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

The following table describes the estimated fees and expenses payable by the registrant in connection with the issuance and distribution of the securities:

Item 15. Indemnification of Directors and Officers.

Section 145 of the DGCL grants us the authority to indemnify each of our directors and officers against all expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by a director or officer that is made a party to any threatened, pending or completed action, suit or proceeding (whether civil, criminal or otherwise), by reason of the fact that such director or officer is or was a director, officer, employee or agent of ours or by reason of the fact that such director or officer, at our request, is or was serving at any other corporation or other entity, in any capacity, if such director or officer acted in good faith and in a manner he or she reasonably believed to be in, or not opposed to, our best interests, and, with respect to any criminal action or proceeding, had no reasonable cause to believe that his or her conduct was unlawful; provided, that in the case of an action, suit or proceeding against a director or officer that is brought by us or in our right, we may indemnify such director or officer only in respect of expenses (including attorneys’ fees) actually and reasonably incurred by such director or officer; provided further, that no such indemnity for expenses may be made with respect to any claim, issue or matter as to which such director or officer shall have been adjudged to be liable to us unless, and only to the extent that, either the Delaware Court of Chancery or the court in which the action, suit or proceeding against such director or officer was brought shall determine upon application that, despite the adjudication of liability to us but in view of all the circumstances of the case, such director or officer is nevertheless fairly and reasonably entitled to indemnity from us for such expenses in an amount deemed proper by such court.

Unless ordered by a court, the determination of whether a then sitting director or officer has met the applicable standard for indemnity, i.e., that the director or officer acted in good faith and in a manner he or she reasonably believed to be in, or not opposed to, our best interests, and, with respect to any criminal action or proceeding, had no reasonable cause to believe that his or her conduct was unlawful, shall be made (i) by a majority vote of the directors who are not parties to such action, suit or proceeding, even though less than a quorum, or (ii) by a committee of such directors designated by majority vote of such directors, even though less than a quorum, or (iii) if there are no such directors, or if such directors so direct, by independent legal counsel in a written opinion, or (iv) by our stockholders.

II-1

Section 145 of the DGCL also authorizes us to advance expenses (including attorneys’ fees) incurred by a director or officer in defending any action, suit or proceeding against the director or officer prior to a determination of whether the director or officer is actually entitled to indemnity and to purchase insurance for the benefit of a director or officer against any liability that may be incurred by reason of the fact that the insured was or is a director or officer, regardless of whether the liability insured could have legally been indemnified by us.

Pursuant to the authority granted us by Section 145 of the DGCL, we have provided in our amended and restated certificate of incorporation and amended and restated bylaws for the indemnification of and advancement of expenses to our directors to the fullest extent authorized or permitted by law as from time to time in effect; provided, however, we are required to indemnify, or advance expenses to, any such director in connection with an action, suit, claim or proceeding initiated by such director only if the initiation of such action, suit, claim or proceeding has been authorized or ratified by our Board of Directors. Our amended and restated bylaws provide that we may, to the extent authorized by our Board of Directors, grant rights of indemnification and the advancement of expenses (including attorney’s fees) to our officers. Our Board of Directors has authorized indemnification of, and advancement of expenses to, our officers serving as such on or after December 1, 2009. The rights authorized by our Board of Directors for the indemnification of, and advancement of expenses to, our officers serving as such on or after December 1, 2009 are the same rights that have been afforded our directors pursuant to our amended and restated certificate of incorporation and amended and restated bylaws.

The employment agreement among us, SemManagement, L.L.C., Rose Rock Midstream GP, LLC, and Carlin G. Conner, our President and Chief Executive Officer, provides Mr. Conner with indemnification and advancement of expenses (including attorney’s fees) to the maximum extent permitted by our amended and restated certificate of incorporation and amended and restated bylaws, including, if applicable, any directors and officers insurance policies, provided such indemnification shall be on terms no less favorable than provided to any of our other executive officers or directors. Pursuant to the employment agreement, we have also agreed to maintain commercially reasonable directors’ and officers’ insurance covering Mr. Conner in such amount and pursuant to such terms as is typical and customary for companies of similar size and nature to us.

We have also purchased a policy of insurance for the benefit of our directors and officers that provides standard liability coverage.

As permitted by Section 102 of the DGCL, our amended and restated certificate of incorporation provides that each of our directors shall not be personally liable to us or our stockholders for monetary damages for breach of fiduciary duty as a director; provided, that a director shall be liable for any breach of such director’s duty of loyalty to us or our stockholders, for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, for liability under Section 174 of the DGCL (involving certain unlawful dividends or stock repurchases), or for any transaction from which such director derived an improper personal benefit.

Item 16. Exhibits.

The following is a list of all exhibits filed as a part of this Registration Statement on Form S-3, including those incorporated by reference herein.

II-2

II-3

II-4

II-5

Item 17. Undertakings.

(a)    The undersigned Registrant hereby undertakes:

(1)    To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i)    To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii)    To reflect in the prospectus any facts or events arising after the effective date of this registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in this registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii)    To include any material information with respect to the plan of distribution not previously disclosed in this registration statement or any material change to such information in this registration statement;

provided, however, that paragraphs (i), (ii) and (iii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2)    That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3)    To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

II-6

(5)    That, for purposes of determining liability under the Securities Act of 1933 to any purchaser:

(A)    Each prospectus filed by the Registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(B)    Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5) or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii) or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which the prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

(6)    That, for the purpose of determining liability of the Registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, the undersigned Registrant undertakes that in a primary offering of securities of the undersigned Registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned Registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i)    Any preliminary prospectus or prospectus of the undersigned Registrant relating to the offering required to be filed pursuant to Rule 424;

(ii)    Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned Registrant or used or referred to by the undersigned Registrant;

(iii)    The portion of any other free writing prospectus relating to the offering containing material information about the undersigned Registrant or its securities provided by or on behalf of the undersigned Registrant; and

(iv)    Any other communication that is an offer in the offering made by the undersigned Registrant to the purchaser.

(b)    The undersigned Registrant hereby undertakes that, for the purposes of determining any liability under the Securities Act of 1933, each filing of the Registrant’s Annual Report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(h)    Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that

II-7

a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

(j)    The undersigned Registrant hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of Section 310 of the Trust Indenture Act in accordance with the rules and regulations prescribed by the Commission under Section 305(b)2 of the Trust Indenture Act.

II-8

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Tulsa, State of Oklahoma, on the 12^th day of July, 2019.

Each of the undersigned officers and directors of SemGroup Corporation, a Delaware corporation, whose signature appears below hereby constitutes and appoints Carlin G. Conner, Robert N. Fitzgerald and Susan S. Lindberg, and each of them, as his or her true and lawful attorneys-in-fact and agents, severally, with full power of substitution and resubstitution, in his or her name and on his or her behalf, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement and to file the same with all exhibits thereto and all documents in connection therewith, with the SEC, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing necessary or appropriate to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated:

II-9

II-10

Exhibit 5

		Conner & Winters, LLP 4000 One Williams Center  |  Tulsa, OK 74172-0148 p (918) 586-5711  |  f (918) 586-8982  |  cwlaw.com

July 12, 2019

SemGroup Corporation

Two Warren Place

6120 S. Yale Avenue, Suite 1500

Tulsa, OK 74136-4231

Ladies and Gentlemen:

We have acted as counsel to SemGroup Corporation, a Delaware corporation (the “Company”), in connection with the filing by the Company of a registration statement on Form S-3 (the “Registration Statement”), with the Securities and Exchange Commission (the “Commission”) pursuant to the Securities Act of 1933, as amended (the “Securities Act”), for the registration of the sale from time to time of an indeterminate amount of (i) debt securities of the Company, which may be either senior debt securities (the “Senior Debt Securities”) or subordinated debt securities (the “Subordinated Debt Securities” and together with the Senior Debt Securities, the “Debt Securities”), (ii) shares of the Company’s Class A common stock, par value $0.01 per share (“Common Stock”), (iii) shares of the Company’s preferred stock, par value $0.01 per share (“Preferred Stock”), (iv) depositary shares representing fractional interests in the Preferred Stock (“Depositary Shares”), (v) warrants representing rights to purchase Debt Securities, Common Stock or Preferred Stock of the Company (“Warrants”), (vi) purchase contracts for the purchase or sale of debt or equity securities of the Company or any combination thereof (“Purchase Contracts”), and (vii) units consisting of one or more Purchase Contracts, Warrants, Debt Securities, shares of Common Stock or any combination of such securities (“Units” and together with the Debt Securities, Common Stock, Preferred Stock, Depositary Shares, Warrants and Purchase Contracts, the “Securities”). The Securities will be sold or delivered from time to time as set forth in the Registration Statement, the prospectus contained therein (the “Prospectus”) and supplements to the Prospectus (the “Prospectus Supplements”).

In connection with this opinion, we have examined originals or copies, certified or otherwise identified to our satisfaction, of (i) the Amended and Restated Certificate of Incorporation, as amended, and Amended and Restated Bylaws of the Company, (ii) the Registration Statement, (iii) the form of Indenture relating to the Senior Debt Securities (the “Senior Indenture”) filed as an exhibit to the Registration Statement, and (iv) the form of Indenture relating to the Subordinated Debt Securities (the “Subordinated Indenture”) filed as an exhibit to the Registration Statement. We have also examined originals or copies, certified or otherwise identified to our satisfaction, of such records of the Company and such agreements, certificates of public officials, certificates of officers or other representatives of the Company and others, and such other documents, certificates and records as we have deemed necessary or appropriate as a basis for the opinions set forth herein.

Dallas  |  Houston  |  NW Arkansas  |  Oklahoma City  |  Tulsa  |  Washington, DC

SemGroup Corporation

July 12, 2019

Page 2

In our examination, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, conformed or photostatic copies and the authenticity of the originals of such latter documents. In making our examination of documents to be executed, we have assumed that at the time of such execution: (i) the parties thereto, including the Company, will have the power, corporate, limited liability company, partnership or other, to enter into and perform all obligations thereunder, (ii) the due authorization by all requisite action, corporate, limited liability company, partnership or other, of the transactions contemplated by such documents, and (iii) the execution and delivery by such parties of such documents, and, as to parties other than the Company, the validity and binding effect of such documents on such parties.

Based upon and subject to the foregoing and the limitations, qualifications, exceptions and assumptions set forth herein, we are of the opinion that:

1.    The Senior Debt Securities proposed to be sold by the Company, when (i) duly authorized by all necessary corporate or other action by the Company, (ii) the trustee under the Senior Indenture has been selected and qualified under the Trust Indenture Act of 1939, as amended, (iii) the Senior Indenture and any supplemental indenture in respect of the Senior Debt Securities have been duly executed and delivered by the Company, (iv) the terms of the Senior Debt Securities have been duly established in accordance with the Senior Indenture and any applicable supplemental indenture relating to the Senior Debt Securities, and (v) the Senior Debt Securities have been duly executed and authenticated in accordance with the Senior Indenture and any related supplemental indenture in respect of the Senior Debt Securities and duly issued and delivered by the Company upon payment of the consideration therefor in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto, will constitute valid and binding obligations of the Company, enforceable in accordance with their terms.

2.    The Subordinated Debt Securities proposed to be sold by the Company, when (i) duly authorized by all necessary corporate or other action by the Company, (ii) the trustee under the Subordinated Indenture has been selected and qualified under the Trust Indenture Act of 1939, as amended, (iii) the Subordinated Indenture and any supplemental indenture in respect of the Subordinated Debt Securities have been duly executed and delivered by the Company, (iv) the terms of the Subordinated Debt Securities have been duly established in accordance with the Subordinated Indenture and any applicable supplemental indenture relating to the Subordinated Debt Securities, and (v) the Subordinated Debt Securities have been duly executed and authenticated in accordance with the Subordinated Indenture and any related supplemental indenture in respect of the Subordinated Debt Securities and duly issued and delivered by the Company upon payment of the consideration therefor in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto, will constitute valid and binding obligations of the Company, enforceable in accordance with their terms.

3.    The shares of Common Stock proposed to be sold by the Company, when (i) all necessary corporate action on the part of the Company has been taken to authorize the issuance and sale of such shares of Common Stock, and (ii) such shares of Common Stock are issued and

SemGroup Corporation

July 12, 2019

Page 3

delivered upon payment of the consideration therefor (not less than the par value of the Common Stock) in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto or upon the conversion, exchange or exercise of any other Security in accordance with the terms of such Security or the instrument governing such Security providing for such conversion, exchange or exercise, will be validly issued, fully paid and non-assessable.

4.    The shares of Preferred Stock proposed to be sold by the Company, when (i) all necessary corporate action on the part of the Company has been taken to authorize the issuance and sale of such series of Preferred Stock, including the adoption of a Certificate of Designations relating to the Preferred Stock (a “Certificate”) and the filing of the Certificate with the Secretary of State of the State of Delaware, and (ii) such shares of Preferred Stock are issued and delivered upon payment of the consideration therefor (not less than the par value of the Preferred Stock) in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto or upon the conversion, exchange or exercise of any other Security in accordance with the terms of such Security or the instrument governing such Security providing for such conversion, exchange or exercise, will be validly issued, fully paid and non-assessable.

5.    The Depositary Shares proposed to be sold by the Company, when (i) all necessary corporate action on the part of the Company has been taken to authorize the issuance and sale of such Depositary Shares, (ii) a Deposit Agreement relating to the Depositary Shares (the “Deposit Agreement”) has been duly authorized and validly executed and delivered, (iii) the Deposit Agreement is consistent with the summary description thereof set forth in the Registration Statement, (iv) the Preferred Stock underlying such Depositary Shares is deposited under the applicable Deposit Agreement with a bank or trust company which meets the requirements for the Depositary set forth in the Registration Statement and any Prospectus Supplement relating thereto, (v) such Depositary Shares or receipts representing such Depositary Shares have been duly executed and authenticated in accordance with the Deposit Agreement, and (vi) such Depositary Shares are issued and delivered by the Company upon payment of the consideration therefor in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto, will be validly issued and will entitle the holders thereof to the rights specified in the Deposit Agreement and the depositary receipts evidencing rights therein.

6.    The Warrants proposed to be sold by the Company, when (i) all necessary corporate action on the part of the Company has been taken to authorize the issuance and sale of the Warrants, (ii) a Warrant Agreement relating to the Warrants (the “Warrant Agreement”) has been duly authorized and validly executed and delivered, (iii) the Warrant Agreement is consistent with the summary description thereof set forth in the Registration Statement, (iv) the Warrants or certificates representing the Warrants have been duly executed and authenticated in accordance with the Warrant Agreement, and (v) the Warrants are issued and delivered by the Company upon payment of the consideration therefor in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto, will constitute valid and binding obligations of the Company, enforceable in accordance with their terms.

7.    The Purchase Contracts proposed to be sold by the Company, when (i) all necessary corporate action on the part of the Company has been taken to authorize the issuance

SemGroup Corporation

July 12, 2019

Page 4

and sale of the Purchase Contracts, (ii) a Purchase Contract Agreement relating to the Purchase Contracts (the “Purchase Contract Agreement”) has been duly authorized and validly executed and delivered, (iii) the Purchase Contract Agreement is consistent with the summary description thereof set forth in the Registration Statement, and (iv) the Purchase Contracts are issued and delivered by the Company upon payment of the consideration therefor in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto, will constitute valid and binding obligations of the Company, enforceable in accordance with their terms.

8.    The Units, when (i) all necessary corporate action on the part of the Company has been taken to authorize the issuance and sale of the Units, (ii) the terms of the collateral arrangements, if any, relating to the Units have been duly established and the agreement(s) relating thereto have been duly executed and delivered and the collateral has been deposited with the collateral agent in accordance with such arrangements, and (iii) the Units are issued and delivered by the Company upon payment of the consideration therefor in the manner contemplated by the Registration Statement and any Prospectus Supplement relating thereto, will constitute valid and binding obligations of the Company, enforceable in accordance with their terms.

The opinions set forth above are subject to the following qualifications, further assumptions and limitations:

(a)    the enforcement of any agreements or instruments may be limited by (1) bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or other similar laws now or hereafter in effect relating to creditors’ rights generally and (2) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or in equity);

(b)    we have assumed that the execution and delivery by the Company of the Senior Indenture, the Subordinated Indenture, the Deposit Agreement, the Warrant Agreement and the Purchase Contract Agreement and the performance by the Company of its obligations thereunder do not and will not violate, conflict with or constitute a default under any agreement or instrument to which the Company or any of its properties is subject; and

(c)    we have assumed, with respect to the opinions set forth above, that there will be a sufficient number of unissued shares of Common Stock and Preferred Stock authorized under the Company’s Amended and Restated Certificate of Incorporation, as amended, and not otherwise reserved for issuance to cover the number of shares of Common Stock and Preferred Stock issued and delivered in the manner contemplated in the Registration Statement and any Prospectus Supplement relating thereto or upon the conversion, exchange or exercise of any other Security in accordance with the terms of such Security or the instrument governing such Security providing for such conversion, exchange or exercise.

Furthermore, we express no opinion as to the validity, binding effect or enforceability of any provision of the Debt Securities, Preferred Stock, Depositary Shares, Warrants, Purchase Contracts or Units which purport to: (i) give the right of specific performance; (ii) alter rules of civil procedure or evidence; (iii) waive defenses, rights, notices, remedies and/or demands absent

SemGroup Corporation

July 12, 2019

Page 5

a showing of clear intent and knowing waiver or to the extent such rights are not waivable under statute or pursuant to public policy; (iv) create and govern a trustee or creditor in possession status; (v) create indemnities or exculpate a party from liability for its own willful misconduct or gross negligence or where such indemnification or exculpation is contrary to public policy or prohibited by law; (vi) prevent the modification of written documents by oral agreements; (vii) provide for recovery of attorneys’ fees or other expenses of enforcement; (viii) provide for additional interest after default or any other provision imposing charges, fees or other amounts not reasonably related to the costs incurred by the payee and which in any such case are held to be a penalty or forfeiture (including, without limitation, any prepayment penalties or premium); or (ix) provide for severability of contractual provisions.

Our opinions set forth above are limited to the laws of the States of Oklahoma and New York, the latter of which are normally applicable to transactions of the type contemplated by the Registration Statement and to the extent that judicial or regulatory orders or decrees or consents, approvals, licenses, authorizations, validations, filings, recordings or registrations with governmental authorities are relevant, to those required under such laws and the General Corporation Law of the State of Delaware, including the applicable provisions of the Delaware Constitution and judicial decisions interpreting those laws as of the date of this opinion (all of the foregoing being referred to as “Opined on Law”). We do not express any opinion with respect to the law of any other jurisdiction other than Opined on Law or as to the effect of any such non opined law on the opinions herein stated.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to our firm in the Prospectus constituting a part of the Registration Statement under the caption, “Legal Matters.” In giving this consent, we do not thereby admit that we are in a category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgated thereunder. The effective date of this opinion is the date first set forth above, and we do not undertake to advise you of any matter brought to our attention thereafter which would or may modify, in whole or in part, any or all of the foregoing.

Very truly yours,

/s/ Conner & Winters, LLP

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We have issued our reports dated February 28, 2019 with respect to the consolidated financial statements and internal control over financial reporting of SemGroup Corporation included in the Annual Report on Form 10-K for the year ended December 31, 2018, which are incorporated by reference in this Registration Statement. We consent to the incorporation by reference of the aforementioned reports in this Registration Statement, and to the use of our name as it appears under the caption “Experts.”

/s/ GRANT THORNTON LLP

Tulsa, Oklahoma

July 12, 2019

Exhibit 23.2

CONSENT OF INDEPENDENT CERTIFIED PUBLIC ACCOUNTANTS

We have issued our report dated February 28, 2019 with respect to the financial statements of White Cliffs Pipeline, L.L.C. included in the Annual Report of SemGroup Corporation on Form 10-K for the year ended December 31, 2018, which is incorporated by reference in this Registration Statement. We consent to the incorporation by reference of the aforementioned report in this Registration Statement, and to the use of our name as it appears under the caption “Experts.”

/s/ GRANT THORNTON LLP

Tulsa, Oklahoma

July 12, 2019

Exhibit 23.3

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

SemGroup Corporation

Tulsa, Oklahoma

We hereby consent to the incorporation by reference in the Prospectus constituting a part of this Registration Statement of our report dated February 24, 2017, relating to the 2016 consolidated financial statements (before the retrospective adjustments to the consolidated financial statements for the subsequent change in segmentation) of SemGroup Corporation, which appears in SemGroup Corporation’s Annual Report on Form 10-K for the year ended December 31, 2018.

We also consent to the reference to us under the caption “Experts” in the Prospectus.

/s/ BDO USA, LLP

Dallas, Texas

July 12, 2019

Exhibit 23.4

CONSENT OF INDEPENDENT AUDITOR

SemGroup Corporation

Tulsa, Oklahoma

We hereby consent to the incorporation by reference in the Prospectus constituting a part of this Registration Statement of our report dated February 24, 2017, relating to the 2016 financial statements of White Cliffs Pipeline, L.L.C., which appears in SemGroup Corporation’s Annual Report on Form 10-K for the year ended December 31, 2018.

We also consent to the reference to us under the caption “Experts” in the Prospectus.

/s/ BDO USA, LLP

Dallas, Texas

July 12, 2019