Filing Details

CUSIP No. 82640U107

Page 2 of 10 Pages

1	NAMES OF REPORTING PERSONS
	THE MANGROVE PARTNERS MASTER FUND, LTD.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
	(a)☒
	(b)☐
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION
	CAYMAN ISLANDS
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER
			0
		6	SHARED VOTING POWER
			7,894,526 (1)
		7	SOLE DISPOSITIVE POWER
			0
		8	SHARED DISPOSITIVE POWER
			7,894,526 (1)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	7,894,526 (1)
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
	☐
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
	9.99% (2)
12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
	OO

Sierra Oncology, Inc. (the “Issuer”)

2150 – 885 West Georgia Street, Vancouver, British Columbia, Canada, V6C 3E8

This Statement is filed on behalf of the following persons (collectively, the “Reporting Persons”):

This Statement relates to Shares (as defined herein) held by the Master Fund, as well as Shares that the Master Fund has the right to acquire within 60 days upon conversion of shares of Series A preferred stock (“Preferred Stock”) held by the Master Fund. Beneficial ownership of the Shares is also claimed by (i) Mangrove Partners which serves as the investment manager of the Master Fund, and (ii) Nathaniel August who is the principal of Mangrove Partners.

The principal business office of Nathaniel August is 645 Madison Avenue, 14th Floor, New York, New York 10022.

The principal business address of the Master Fund and Mangrove Partners is c/o Maples Corporate Services, Ltd., PO Box 309, Ugland House, South Church Street, George Town, Grand Cayman, Cayman Islands KY1-1104.

Each of the Master Fund and Mangrove Partners is organized as a limited liability exempted company under the laws of the Cayman Islands. Nathaniel August is a citizen of the United States.

Common Stock, par value $0.001 per share (the “Shares”)

82640U107

This Item 3 is not applicable.

As of November 13, 2019 and the date hereof, each of the Master Fund, Mangrove Partners, and Mr. August may be deemed the beneficial owner of 7,894,526 Shares. This amount includes: (i) 3,558,523 Shares held by the Master Fund; and (ii) 4,336,003 Shares obtainable upon conversion of Preferred Stock held by the Master Fund.  As the investment manager of the Master Fund, Mangrove Partners may be deemed the beneficial owner of the Shares owned by the Master Fund. Mr. August, as the principal of Mangrove Partners, may be deemed the beneficial owner of the Shares owned by the Master Fund.

The amount of Shares reported as beneficially owned by the Reporting Persons excludes shares of Preferred Stock held by the Master Fund which the Reporting Persons do not currently have the right to convert into Shares, due to a 9.99% blocker on the conversion rights of each of the Preferred Stock. Specifically, the Certificate of Designation for the Preferred Stock provides that the holder of Preferred Stock will not have the right to convert, subject to certain exceptions, the Preferred Stock for Shares if, as a result of such conversion, the holder, together with its affiliates and other attribution parties, would own more than 9.99% of the total number of Shares then issued and outstanding.  Without giving effect to the 9.99% blocker provision, the Preferred Stock held by the Master Fund would be convertible into an aggregate of 14,393,651 Shares.

The amount of Shares reported as beneficially owned by the Reporting Persons also excludes an aggregate of 19,142,025 Shares underlying Series A Warrants and Series B Warrants held by the Master Fund that the Reporting Persons do not currently have the right to exercise, due to conditions outside of their control.  As such, the Reporting Persons are not deemed to beneficially own such Shares.

The filing of this Schedule 13G shall not be construed as an admission that the Reporting Persons are, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, the beneficial owners of any of the Shares reported herein. Each of the Reporting Persons specifically disclaims beneficial ownership of the Shares reported herein that are not directly owned by such Reporting Person.

Each of the Master Fund, Mangrove Partners, and Mr. August may be deemed the beneficial owner of approximately 9.99% of Shares outstanding.

The beneficial ownership percentages reported in this Statement are based on the sum of (i) 74,688,283 Shares outstanding as of October 31, 2019, according to the Issuer’s Form 8-K, filed on November 04, 2019 and (ii) 4,336,003 Shares issuable upon conversion of the Preferred Stock held by the Master Fund, which is the maximum number of Shares currently issuable upon the voluntary conversion of Preferred Stock by the Reporting Person under the 9.99% blocker, and which Shares are added to the total Shares outstanding pursuant to Rule 13d-3(d)(1)(i) under the Act.

This Item 5 is not applicable.

This Item 6 is not applicable.

This Item 7 is not applicable.

See disclosures in Item 2 and Exhibit A.

This Item 9 is not applicable.

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under §240.14a-11.

SIGNATURE

EXHIBIT INDEX