SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

Reata Pharmaceuticals, Inc.

(Name of Issuer)

Class A Common Stock, $0.001 par value

(Title of Class of Securities)

75615P 103

(CUSIP Number)

June 1, 2016

(Date of Event which Requires Filing of this Statement)

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

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).

(a) Includes (i) 32,864 shares of Class A common stock, par value $0.001 per share (“Class A Common Stock”) of Reata Pharmaceuticals, Inc. (the “Issuer”); and (ii) 365,800 shares of Class B common stock, par value $0.001 per share (“Class B Common Stock”) of the Issuer, which Class B Common Stock may be converted on a one-to-one basis within 60 days into Class A Common Stock, each such share of Class A and Class B Common Stock held directly by Stapleton Pharma LLC and over which it may be deemed to exercise shared voting and dispositive power.

(b) Based on 7,643,401 shares of Class A Common Stock outstanding.

(a) Includes (i) 32,864 shares of Class A Common Stock and (ii) 365,800 shares of Class B Common Stock, which Class B Common Stock may be converted on a one-to-one basis within 60 days into Class A Common Stock, each such share of Class A and Class B Common Stock held directly by Stapleton Pharma LLC and over which Mr. Stapleton may be deemed to exercise shared voting and dispositive power.

(b) Based on 7,643,401 shares of Class A Common Stock outstanding.

2801 Gateway Drive, Suite 150

Irving, Texas 75063

Stapleton Pharma LLC

Craig R. Stapleton

The business address of Stapleton Pharma LLC and Mr. Stapleton 55 Old Field Point Road, 2nd Floor, Greenwich, Connecticut 06830.

Stapleton Pharma LLC is a Connecticut limited liability company.

Mr. Stapleton is a United States citizen.

Stapleton Pharma LLC and Mr. Stapleton may each be deemed to beneficially own 398,664 shares of Class A Common Stock, representing approximately 4.98% of the outstanding shares of Class A Common Stock.

Stapleton Pharma LLC may be deemed to have shared voting and dispositive power with respect to 398,664 shares of Class A Common Stock (by virtue of its direct ownership of 32,864 shares of Class A Common Stock and 365,800 shares of Class B common stock, par value $0.001 per share (“Class B Common Stock”) of the Issuer). As the sole managing member of Stapleton Pharma LLC, Mr. Stapleton may also be deemed to have shared voting and dispositive power with respect to 398,664 shares of Class A Common Stock.

Prior to the Issuer’s initial public offering of Class A Common Stock, which closed on June 1, 2016 (the “IPO”), Stapleton Pharma LLC held 398,664 shares of Class B Common Stock. In connection with the IPO, 32,864 of such shares of Class B Common Stock converted into an equal number of shares of Class A Common Stock and Stapleton Pharma LLC acquired an additional 420,000 shares of Class A Common Stock. On June 9, 2016, Stapleton Pharma LLC distributed each of the 420,000 shares of Class A Common Stock that it acquired in the IPO to its members, on a pro rata basis (the “In-Kind Distribution”). As a result of the In-Kind Distribution, Stapleton Pharma LLC and Mr. Stapleton no longer beneficially own more than five percent of the Class A Common Stock as of the date hereof.

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 Issuer 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

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

SIGNATURE

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

LIST OF EXHIBITS

Exhibit 99.1

JOINT FILING AGREEMENT

Pursuant to Rule 13d-1(k)(1)(iii) of the Securities Exchange Act of 1934, as amended, each of the undersigned hereby consent to the joint filing on its behalf of a single Schedule 13D and any amendments thereto, with respect to the beneficial ownership by each of the undersigned of the shares of Class A Common Stock of Reata Pharmaceuticals, Inc. The undersigned hereby further agree that this Joint Filing Agreement be included as an exhibit to such statement and any such amendment. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others. The undersigned hereby further agree that this Joint Filing Agreement may be executed in any number of counterparts, each of which when so executed shall be deemed to be an original, but all of which counterparts shall together constitute one and the same instrument.