UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934*

(Amendment No. 2)

SEMGROUP CORPORATION

(Name of Issuer)

Class A Common Stock, par value $0.01 per share

(Title of Class of Securities)

81663A105

(CUSIP Number)

John G. Finley

c/o The Blackstone Group L.P.

345 Park Avenue

New York, New York 10154

Tel: (212) 583-5000

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

March 30, 2018

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box:  ☐

NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No. 81663A105 2

1	NAMES OF REPORTING PERSONS   Harvest Fund Holdco L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   PN

SCHEDULE 13D

CUSIP No. 81663A105 3

1	NAMES OF REPORTING PERSONS   Blackstone Harvest Holdco L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   OO

SCHEDULE 13D

CUSIP No. 81663A105 4

1	NAMES OF REPORTING PERSONS   Blackstone Intermediary Holdco L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   OO

SCHEDULE 13D

CUSIP No. 81663A105 5

1	NAMES OF REPORTING PERSONS   Blackstone Advisory Partners L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   PN

SCHEDULE 13D

CUSIP No. 81663A105 6

1	NAMES OF REPORTING PERSONS   Blackstone Advisory Services L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   OO

SCHEDULE 13D

CUSIP No. 81663A105 7

1	NAMES OF REPORTING PERSONS   Blackstone Holdings I L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   PN

SCHEDULE 13D

CUSIP No. 81663A105 8

1	NAMES OF REPORTING PERSONS   Blackstone Holdings I/II GP Inc.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   CO

SCHEDULE 13D

CUSIP No. 81663A105 9

1	NAMES OF REPORTING PERSONS   The Blackstone Group L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   PN

SCHEDULE 13D

CUSIP No. 81663A105 10

1	NAMES OF REPORTING PERSONS   Blackstone Group Management L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   Delaware

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   OO

SCHEDULE 13D

CUSIP No. 81663A105 11

1	NAMES OF REPORTING PERSONS   Stephen A. Schwarzman
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)   (a)  ☐        (b)  ☒
3	SEC USE ONLY
4	SOURCE OF FUNDS (See Instructions)   OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)   ☐
6	CITIZENSHIP OR PLACE OF ORGANIZATION   United States of America

NUMBER OF SHARES   BENEFICIALLY   OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER   0
	8	SHARED VOTING POWER   0
	9	SOLE DISPOSITIVE POWER   0
	10	SHARED DISPOSITIVE POWER   0

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON    0
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)   ☐
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)    0.0%
14	TYPE OF REPORTING PERSON (See Instructions)   IN

Explanatory Note

This Amendment No. 2 (“Amendment No. 2”) to Schedule 13D relates to the shares of Class A Common Stock, par value $0.01 per share (the “Common Stock”), of SemGroup Corporation, a Delaware corporation (the “Issuer”), and amends the initial statement on Schedule 13D filed on October 26, 2017 (the “Original Schedule 13D”), as amended by Amendment No. 1 to the Schedule 13D filed on November 6, 2017 (the Original Schedule 13D, as amended, the “Schedule 13D”). Capitalized terms used but not defined in this Amendment No. 2 shall have the same meanings ascribed to them in the Schedule 13D.

Harvest Fund Advisors LLC (“HFA”), an investment management firm with over $10 billion in assets under management, initially filed a Schedule 13G with respect to the Common Stock of the Issuer pursuant to Rule 13d-1(b) under the Securities Exchange Act of 1934, as amended, on February 5, 2016. On October 16, 2017, a subsidiary of The Blackstone Group L.P. acquired HFA. In connection with that acquisition, The Blackstone Group L.P. and certain of its affiliates (the “Blackstone Reporting Persons”) may have been deemed to have become the beneficial owner of the securities beneficially owned by HFA at such time, including the securities of the Issuer, and HFA and the Blackstone Reporting Persons together reported beneficial ownership of such securities on a Schedule 13D.

As of March 30, 2018, the business comprising HFA (the “HFA Business”) will calculate and report beneficial ownership over securities separately from the rest of The Blackstone Group L.P. and its affiliates other than those comprising the HFA Business (“Blackstone”), in accordance with Securities and Exchange Commission Release No. 34-39538 (the “Release”). As a result of the foregoing, and as reflected in this Amendment, the Blackstone Reporting Persons ceased to be beneficial owners of more than 5% of the securities of the Issuer on March 30, 2018. The securities of the Issuer beneficially owned by the HFA Business are being separately reported on a Schedule 13G, which filing will not reflect securities, if any, beneficially owned by Blackstone, whose ownership has been disaggregated from that of the HFA Business in accordance with the Release.

Item 2. Identity and Background

Item 2 of the Schedule 13D is hereby amended to reflect the removal of HFA as a Reporting Person on this Schedule 13D as described in the Explanatory Note above.

Item 5. Interest in Securities of the Issuer.

Item 5 of the Schedule 13D is hereby amended and restated as follows:

(a) and (b). None of the Reporting Persons beneficially owns any Common Stock as of March 30, 2018.

(c) Except as set forth in Schedule 1 of this Schedule 13D (which reflects transactions prior to the disaggregation of the HFA Business from the rest of Blackstone as of March 30, 2018), as of March 30, 2018, none of the Reporting Persons has effected any transaction in the past 60 days in Common Stock.

(d) Not applicable.

(e) Upon the disaggregation of the HFA Business from the rest of Blackstone as of March 30, 2018, the Reporting Persons ceased to beneficially own more than five percent of the outstanding Common Stock.

SIGNATURES

After reasonable inquiry and to the best of its or his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: April 3, 2018

HARVEST FUND HOLDCO L.P.
By: Blackstone Harvest Holdco L.L.C., its General Partner
By:	/s/ Marisa Beeney
Name:	Marisa Beeney
Title:	Authorized Person
BLACKSTONE HARVEST HOLDCO L.L.C.
By: Blackstone Intermediary Holdco L.L.C., its Sole Member
By: Blackstone Advisory Partners L.P., its Sole Member
By: Blackstone Advisory Services L.L.C., its General Partner
By: Blackstone Holdings I L.P., its Sole Member
By: Blackstone Holdings I/II GP Inc., its General Partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
BLACKSTONE INTERMEDIARY HOLDCO L.L.C.
By: Blackstone Advisory Partners L.P., its Sole Member
By: Blackstone Advisory Services L.L.C., its General Partner
By: Blackstone Holdings I L.P., its Sole Member
By: Blackstone Holdings I/II GP Inc., its General Partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
BLACKSTONE ADVISORY PARTNERS L.P.
By: Blackstone Advisory Services L.L.C., its General Partner
By: Blackstone Holdings I L.P., its Sole Member
By: Blackstone Holdings I/II GP Inc., its General Partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer

[SemGroup Corporation – Schedule 13D/A]

BLACKSTONE ADVISORY SERVICES L.L.C.
By: Blackstone Holdings I L.P., its Sole Member
By: Blackstone Holdings I/II GP Inc., its General Partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
BLACKSTONE HOLDINGS I L.P.
By: Blackstone Holdings I/II GP Inc., its General Partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
BLACKSTONE HOLDINGS I/II GP INC.
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
THE BLACKSTONE GROUP L.P.
By: Blackstone Group Management L.L.C., its General Partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
BLACKSTONE GROUP MANAGEMENT L.L.C.
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
/s/ Stephen A. Schwarzman
Stephen A. Schwarzman

[SemGroup Corporation – Schedule 13D/A]

SCHEDULE 1

As of March 30, 2018, the below reflects the transactions in Common Stock effected by the Reporting Persons during the past 60 days. All transactions occurred in the open market.    

Date	Common Stock Purchase/(Sold)			Weighted Average Trading Price per Common Stock		Seller/Purchaser
2/1/2018		52,912		$	28.8824	Harvest Fund Advisors LLC*
2/7/2018		17,078		$	27.5201	Harvest Fund Advisors LLC*
2/15/2018		5,265		$	27.2750	Harvest Fund Advisors LLC*
2/15/2018		(5,265	)	$	27.2750	Harvest Fund Advisors LLC*
2/22/2018		(18,916	)	$	26.3676	Harvest Fund Advisors LLC*
2/23/2018		(50,000	)	$	25.1126	Harvest Fund Advisors LLC*
2/26/2018		5,305		$	23.4000	Harvest Fund Advisors LLC*
2/26/2018		(5,305	)	$	23.4000	Harvest Fund Advisors LLC*
2/27/2018		13,226		$	23.1250	Harvest Fund Advisors LLC*
2/27/2018		(13,226	)	$	23.1250	Harvest Fund Advisors LLC*
3/1/2018		3,517		$	22.4335	Harvest Fund Advisors LLC*
3/2/2018		5,000		$	22.3270	Harvest Fund Advisors LLC*
3/5/2018		5,701		$	22.5180	Harvest Fund Advisors LLC*
3/13/2018		(26,478	)	$	22.7093	Harvest Fund Advisors LLC*
3/14/2018		(6,059	)	$	22.4778	Harvest Fund Advisors LLC*
3/15/2018		(1,100	)	$	22.1136	Harvest Fund Advisors LLC*
3/16/2018		1,042		$	22.1250	Harvest Fund Advisors LLC*
3/16/2018		(1,042	)	$	22.1250	Harvest Fund Advisors LLC*
3/16/2018		(6,000	)	$	22.5275	Harvest Fund Advisors LLC*
3/26/2018		12,559		$	21.1000	Harvest Fund Advisors LLC*
3/26/2018		(12,559	)	$	21.1000	Harvest Fund Advisors LLC*
3/28/2018		8,800		$	20.4614	Harvest Fund Advisors LLC*
3/28/2018		(15,000	)	$	20.5328	Harvest Fund Advisors LLC*
3/29/2018		2,000		$	21.3575	Harvest Fund Advisors LLC*

* Reflects transactions in the Common Stock effected by Harvest Fund Advisors LLC on behalf of the funds and accounts it manages on or prior to the disaggregation of the HFA Business from the rest of Blackstone as of March 30, 2018.