13G Filing: Perceptive Advisors and Global Blood Therapeutics Inc (GBT)

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Item 1(a).

Name of Issuer:

Global Blood Therapeutics, Inc. (the Issuer)

Item 1(b).

Address of Issuers Principal Executive Offices:

171 Oyster Point
Boulevard, Suite 300

South San Francisco, CA 94080

Item 2(a).

Names of Persons Filing:

The names of the persons filing this report
(collectively, the Reporting Persons) are:

Perceptive Advisors LLC (Perceptive Advisors)

Joseph Edelman (Mr. Edelman)

Perceptive Life Sciences Master Fund, Ltd. (the Master Fund)

Item 2(b).

Address of Principal Business Office or, if None, Residence:

The address of the
principal business office of each of the Reporting Persons is:

51 Astor Place, 10th Floor

New York, NY 10003

Item 2(c).

Citizenship:

Perceptive Advisors is a Delaware limited liability company

Mr. Edelman is a United States citizen

The Master Fund is a Cayman Islands corporation

Item 2(d).

Title of Class of Securities:

Common Stock, $.001 par value
(Common Stock)

Item 2(e).

CUSIP Number:

37890U 10 8

Item 3.

If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Not applicable.

Item 4.

Ownership.

The information required by this item with respect to each Reporting
Person is set forth in Rows 5 through 9 and 11 of the cover page to this Schedule 13G. The ownership percentages reported are based on 46,007,393 outstanding shares of Common Stock, as reported in the Issuers prospectus filed on December 19,
2017.