UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Amendment No. 1

Under the Securities Exchange Act of 1934

FireEye, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

31816Q101

(CUSIP Number)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨ Rule 13d-1(b)

¨ Rule 13d-1(c)

x Rule 13d-1(d)

The information required in 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).

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

FireEye, Inc.

1440 McCarthy Blvd.

Milpitas, CA 95035

525 University Ave, Suite 800

Palo Alto, CA 94301

525 University Ave, Suite 800

Palo Alto, CA 94301

525 University Ave, Suite 800

Palo Alto, CA 94301

525 University Ave, Suite 800

Palo Alto, CA 94301

525 University Ave, Suite 800

Palo Alto, CA 94301

525 University Ave, Suite 800

Palo Alto, CA 94301

This statement is filed by Norwest Venture Partners IX, LP on behalf of all of the persons listed above pursuant to Rule 13d-1(d) and Rule 13d-1(k). Norwest Venture Partners IX, LP is a Delaware limited partnership, whose general partner is Genesis VC Partners IX, LLC. NVP Associates, LLC is the managing member of Genesis VC Partners IX, LLC. Promod Haque, Jeffrey Crowe and Matthew D. Howard are co-Chief Executive Officers of NVP Associates, LLC.

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Common Stock

31816Q101

(1) Norwest Venture Partners IX, LP (“NVP IX”): At December 31, 2104, NVP IX owned of record 0 shares of Issuer’s common stock (“Common Stock”). This amount represents 0% of the total shares of Common Stock outstanding at this date.

(2) Genesis VC Partners IX, LLC (“Genesis IX”): At December 31, 2014, Genesis IX may be deemed to have beneficially owned, by virtue of its status as general partner of NVP IX, 0 shares of Common Stock. This amount represents 0% of the total shares of Common Stock outstanding at this date.

(3) NVP Associates, LLC (“NVP Associates”): At December 31, 2014, NVP Associates may be deemed to have beneficially owned 0 shares of Common Stock consisting of the following: (1) 0 shares of Common Stock by virtue of its status as managing member of Genesis IX, the general partner of NVP IX, the record owner of such shares; and (2) 0 shares of Common Stock by virtue of its status as managing member of Itasca VC Partners VIII, LLP (“Itasca VIII”), the general partner of Norwest Venture Partners VIII, LP (“NVP VIII”), the record owner of such shares. This amount represents 0% of the total shares of Common Stock outstanding at this date.

(4) Promod Haque: At December 31, 2014, Promod Haque may be deemed to have beneficially owned 0 shares of Common Stock consisting of the following: (1) 0 shares of Common Stock by virtue of his status as co-Chief Executive Officer of NVP Associates, the managing member of Genesis IX, the general partner of NVP IX, the record owner of such shares; and (2) 0 shares of Common Stock by virtue of his status as co-Chief Executive Officer of NVP Associates, the managing member of Itasca VIII, the general partner of NVP VIII, the record owner of such shares. This amount represents 0% of the total shares of Common Stock outstanding at this date.

(5) Jeffrey Crowe: At December 31, 2014, Jeffrey Crowe may be deemed to have beneficially owned 0 shares of Common Stock consisting of the following: (1) 0 shares of Common Stock by virtue of his status as co-Chief Executive Officer of NVP Associates, the managing member of Genesis IX, the general partner of NVP IX, the record owner of such shares; and (2) 0 shares of Common Stock by virtue of his status as co-Chief Executive Officer of NVP Associates, the managing member of Itasca VIII, the general partner of NVP VIII, the record owner of such shares. This amount represents 0% of the total shares of Common Stock outstanding at this date.

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(6) Matthew D. Howard: At December 31, 2014, Matthew D. Howard may be deemed to have beneficially owned 0 shares of Common Stock consisting of the following: (1) 0 shares of Common Stock by virtue of his status as co-Chief Executive Officer of NVP Associates, the managing member of Genesis IX, the general partner of NVP IX, the record owner of such shares; and (2) 0 shares of Common Stock by virtue of his status as co-Chief Executive Officer of NVP Associates, the managing member of Itasca VIII, the general partner of NVP VIII, the record owner of such shares. This amount represents 0% of the total shares of Common Stock outstanding at this date.

If this statement is being filed to report the fact that as of the date hereof the reporting persons have ceased to be beneficial owners of more than five percent of the class of securities, check the following  x.

Not Applicable

Not Applicable

Not Applicable

Not Applicable

Not applicable.

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Signature.

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete, and correct.

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AGREEMENT

The undersigned hereby agree that this Schedule 13G to which this Agreement is attached shall be filed by Norwest Venture Partners IX, LP on its own behalf and on behalf of (a) Genesis VC Partners IX, LLC, a Delaware limited liability company, (b) NVP Associates, LLC, a Delaware limited liability company, (c) Promod Haque, (d) Jeffrey Crowe and (e) Matthew D. Howard.

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