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 the disclosures provided in a prior cover page.

Names of Reporting Persons

Thomas B. Neff

Check the Appropriate Box if a Member of a Group (see instructions)

(a)  ☐        (b)  ☐

SEC USE ONLY

Citizenship or Place of Organization

United States

Number of

Shares

Beneficially  

Owned by

Each

Reporting

Person With:

Sole Voting Power

4,391,546 shares⁽¹⁾

Shared Voting Power

Not applicable.

Sole Dispositive Power

4,391,546 shares⁽¹⁾

Shared Dispositive Power

Not applicable.

Aggregate Amount Beneficially Owned by Each Reporting Person

4,391,546 shares⁽¹⁾

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (see instructions) ☒

19,500 shares⁽²⁾

Percent of Class Represented by Amount in Row 9

5.1%⁽³⁾

Type of Reporting Person (see instructions)

IN

Includes 87,450 shares of Common Stock held by the Thomas B. Neff Family Partnership, 60,946 shares held by BioGrowth Partners, L.P., and 1,781,071 shares of Common Stock issuable pursuant to stock options exercisable within 60 days of December 31, 2018 and 4,612 shares of common stock issuable pursuant to restricted stock units within 60 days of December 31, 2018.

Shares held by Reporting Person’s spouse over which the Reporting Person has no voting or dispositive power.

The percentage calculation is based on 84,978,056 shares of Common Stock outstanding on October 31, 2018 as reported in the Issuer’s quarterly report on Form 10-Q as filed with the SEC on November 8, 2018, plus the Reporting Person’s options exercisable within 60 days of December 31, 2018 and restricted stock units issuable within 60 days of December 31, 2018.

Names of Reporting Persons

Thomas B. Neff Family Partnership

Check the Appropriate Box if a Member of a Group (see instructions)

(a)  ☐        (b)  ☐

SEC USE ONLY

Citizenship or Place of Organization

USA

Number of

Shares

Beneficially  

Owned by

Each

Reporting

Person With:

Sole Voting Power

87,450 shares

Shared Voting Power

Not applicable.

Sole Dispositive Power

87,450 shares

Shared Dispositive Power

Not applicable.

Aggregate Amount Beneficially Owned by Each Reporting Person

87,450 shares

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (see instructions) ☐

Percent of Class Represented by Amount in Row 9

0.1%⁽¹⁾

Type of Reporting Person (see instructions)

OO

The percentage calculation is based on 84,978,056 shares of Common Stock outstanding on October 31, 2018 as reported in the Issuer’s quarterly report on Form 10-Q as filed with the SEC on November 8, 2018.

Names of Reporting Persons

BioGrowth Partners, L.P.

Check the Appropriate Box if a Member of a Group (see instructions)

(a)  ☐        (b)  ☐

SEC USE ONLY

Citizenship or Place of Organization

USA

Number of

Shares

Beneficially  

Owned by

Each

Reporting

Person With:

Sole Voting Power

60,946 shares

Shared Voting Power

Not applicable.

Sole Dispositive Power

60,946 shares

Shared Dispositive Power

Not applicable.

Aggregate Amount Beneficially Owned by Each Reporting Person

60,946 shares

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (see instructions) ☐

Percent of Class Represented by Amount in Row 9

0.1%⁽¹⁾

Type of Reporting Person (see instructions)

OO

The percentage calculation is based on 84,978,056 shares of Common Stock outstanding on October 31, 2018 as reported in the Issuer’s quarterly report on Form 10-Q as filed with the SEC on November 8, 2018.

Name of Issuer: FibroGen, Inc.

Address of Issuer’s Principal Executive Offices: 409 Illinois St., San Francisco, CA 94158

Name of Person Filing:

Address of Principal Business Office or, if none, Residence: The address and principal business office of the Reporting Person is:

Citizenship:

Title of Class of Securities: Common Stock

CUSIP Number: 31572Q808

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:

☐ Broker or dealer registered under Section 15 of the Act (15 U.S.C. 78o);

☐ Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

☐ Insurance company as defined in section 3(a)19) of the Act (15 U.S.C. 78c);

☐ Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

☐ An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

☐ An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

☐ A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

☐ A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

☐ A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

☐ A non-U.S. institution in accordance with §240.13d–1(b)(1)(ii)(J);

☐ Group, in accordance with §240.13d–1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with §240.13d–1(b)(1)(ii)(J), please specify the type of institution:         

Ownership

Amount Beneficially Owned:

Percent of Class:

Number of shares as to which the person has:

Sole power to vote or to direct the vote:

Shared power to vote or to direct the vote:

Sole power to dispose or to direct the disposition of:

Shared power to dispose or to direct the disposition of:

Includes 87,450 shares of Common Stock held by the Thomas B. Neff Family Partnership, 60,946 shares held by BioGrowth Partners, L.P., and 1,781,071 shares of Common Stock issuable pursuant to stock options exercisable within 60 days of December 31, 2018 and 4,612 shares of common stock issuable pursuant to restricted stock units within 60 days of December 31, 2018.

Ownership of 5 Percent or Less of a Class

Ownership of More than 5 Percent on Behalf of Another Person

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person.

Identification and Classification of Members of the Group

Notice of Dissolution of a Group

Certification