UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

SCHEDULE 13D

[Rule 13d-101]

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1(a)

AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2(a)

REATA PHARMACEUTICALS, INC.

(Name of Issuer)

CLASS A COMMON STOCK, $.001 PAR VALUE

(Title of Class of Securities)

75615P 103

(CUSIP Number)

WILLIAM E. ROSE

C/O CARDINAL INVESTMENT COMPANY, INC.

3963 MAPLE AVENUE, SUITE 200

DALLAS, TEXAS 75219

(214) 871-6809

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

May 25, 2016

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note. Schedules filed in paper format shall include a signed original and five copes of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

The information required on 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 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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ITEM 1. SECURITY AND ISSUER.

This Schedule 13D relates to the Class A common stock, par value $0.001 per share (the “Class A Common Stock”), of Reata Pharmaceuticals, Inc., a Delaware corporation (the “Issuer”). The principal executive offices of the Issuer are located at 2801 Gateway Drive, Suite 150, Irving, Texas 75063.

ITEM 2. IDENTITY AND BACKGROUND.

The names of the persons filing this Statement (the “Reporting Persons”) include:

The principal business address for each of the Reporting Persons and Ms. Marcus is c/o Cardinal Investment Company, Inc., 3963 Maple Avenue, Suite 200, Dallas, Texas 75219.

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None of the Reporting Persons nor Ms. Marcus have, during the last five years, been convicted in a criminal proceeding or been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

ITEM 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

The information set forth in Item 2, Item 5 and Item 6 is hereby incorporated by reference in its entirety.

Prior to the Issuer’s initial public offering of Class A Common Stock (the “IPO”), each of Reporting Persons held the following outstanding shares of Class B common stock of the Issuer, par value $0.001 per share (“Class B Common Stock”):

Such shares were acquired over several years in private placements using the personal funds and working capital of Edward W. Rose III, Mr. Gale and Mr. Rose and their related investment vehicles. Shares of Class B Common Stock are convertible into shares of Class A Common Stock on a one-for-one basis (a) at the holder’s election at any time after the date that is six months following the date of the closing of the initial public offering of the Shares, (b) at the holder’s election prior to that time subject to certain conditions, or (c) at the option of the Issuer’s board of directors, in its sole discretion, at any time or multiple times from time to time on or before the closing of the initial public offering.

Upon effectiveness of the Issuer’s Registration Statement on Form 8-A on May 25, 2016, filed in connection with the Issuer’s initial public offering of Class A Common Stock (the “IPO”), each of the Reporting Persons became the deemed beneficial owners of one share of Class A Common Stock for every share of Class B Common Stock owned by such Reporting Person. Upon the closing of the IPO, approximately 8% of the shares of Class B Common Stock of each of the Reporting Persons automatically converted into shares of Class A Common Stock for no additional consideration.

Additionally, Montrose LP acquired 143,000 shares of Class A Common Stock at a purchase price of $11.00 per share in the IPO with limited partnership funds, which consist of working capital of the partnership and may include borrowings under a working capital line of credit with JP Morgan Chase Bank. Puffin Partners acquired 957,000 shares of Class A Common Stock at a purchase price of $11.00 per share in the IPO with limited partnership funds, which consist of working capital of the partnership.

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ITEM 4. PURPOSE OF TRANSACTION.

The Class A Common Stock and Class B Common Stock described herein was acquired by the Reporting Persons for investment purposes. The Reporting Persons have no present plans or proposals for disposition of the shares beneficially owned by him or for acquisition of additional shares. The Reporting Persons, however, expect to evaluate on a continuing basis their goals and objectives, other business opportunities available to them, and general economic and equity market conditions, as well as the Issuer’s business operations and prospects. Based on such evaluations, the Reporting Persons may change their plans and intentions and may determine to sell or otherwise dispose of some or all of the shares beneficially owned by them or to acquire additional shares. In addition, the Reporting Persons may, from time to time, transfer shares beneficially owned by them for tax or other economic planning purposes.

Except as set forth above, the Reporting Persons have no present plans or intentions which would result in or relate to any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D.

ITEM 5. INTEREST IN SECURITIES OF ISSUER.

The information set forth in Item 2, Item 3 and Item 6 is hereby incorporated by reference in its entirety.

(2) The Estate may be deemed to beneficially own 2,046,718 shares of Class A Common Stock, representing approximately 21.50% of the outstanding shares of Class A Common Stock.

(3) Mrs. Rose may be deemed to beneficially own 95,662 shares of Class A Common Stock, representing approximately 1.24% of the outstanding shares of Class A Common Stock.

(4) The Rose IRA may be deemed to beneficially own 95,662 shares of Class A Common Stock, representing approximately 1.24% of the outstanding shares of Class A Common Stock.

(5) The 2001 Trust may be deemed to beneficially own 235 shares of Class A Common Stock, representing approximately 0.00% of the outstanding shares of Class A Common Stock.

(6) The 2002 Trust may be deemed to beneficially own 537 shares of Class A Common Stock, representing approximately 0.01% of the outstanding shares of Class A Common Stock.

(7) Mr. Gale may be deemed to beneficially own 3,117,017 shares of Class A Common Stock, representing approximately 32.44% of the outstanding shares of Class A Common Stock.

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(8) The Gale IRA may be deemed to beneficially own 342 shares of Class A Common Stock, representing approximately 0.00% of the outstanding shares of Class A Common Stock.

(9) Puffin Partners may be deemed to beneficially own 957,000 shares of Class A Common Stock, representing approximately 12.52% of the outstanding shares of Class A Common Stock.

(10) Puffin GP may be deemed to beneficially own 957,000 shares of Class A Common Stock, representing approximately 12.52% of the outstanding shares of Class A Common Stock.

(11) Montrose LP may be deemed to beneficially own 143,000 shares of Class A Common Stock, representing approximately 1.87% of the outstanding shares of Class A Common Stock.

(12) Montrose GP may be deemed to beneficially own 143,000 share of Class A Common Stock, representing approximately 1.87% of the outstanding shares of Class A Common Stock.

(b) (1) Mr. Rose may be deemed to have sole voting power with respect to 140,926 shares of common stock (comprised of 11,618 shares of Class A Common Stock and 129,308 shares of Class B Common Stock), shared voting power with respect to 1,100,772 shares of common stock (comprised of 1,100,065 shares of Class A Common Stock and 707 shares of Class B Common Stock), sole dispositive power with respect to 140,926 shares of common stock (comprised of 11,618 shares of Class A Common Stock and 129,308 shares of Class B Common Stock), and shared dispositive power with respect to 1,100,772 shares of common stock (comprised of 1,100,065 shares of Class A Common Stock and 707 shares of Class B Common Stock).

(2) The Estate may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 2,046,718 shares of common stock (comprised of 168,720 shares of Class A Common Stock and 1,877,998 shares of Class B Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 2,046,718 shares of common stock (comprised of 168,720 shares of Class A Common Stock and 1,877,998 shares of Class B Common Stock).

(3) Mrs. Rose may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 95,662 shares of common stock (comprised of 7,886 shares of Class A Common Stock and 87,776 shares of Class B Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 95,662 shares of common stock (comprised of 7,886 shares of Class A Common Stock and 87,776 shares of Class B Common Stock).

(4) Rose IRA may be deemed to have sole voting power with respect to 0 shares of common stock, and shared voting power with respect to 95,662 shares of common stock (comprised of 7,886 shares of Class A Common Stock and 87,776 shares of Class B Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 95,662 shares of common stock (comprised 7,886 shares of Class A Common Stock and 87,776 shares of Class B Common Stock).

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(5) The 2001 Trust may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 235 shares of common stock (comprised of 20 shares of Class A Common Stock and 215 shares of Class B Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 235 shares of common stock (comprised of 20 shares of Class A Common Stock and 215 shares of Class B Common Stock).

(6) The 2002 Trust may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 537 shares of common stock (comprised of 45 of Class A Common Stock and 492 shares of Class B Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared voting power with respect to 537 shares of common stock (comprised of 45 shares of Class A Common Stock and 492 shares of Class B Common Stock).

(7) Mr. Gale may be deemed to have sole voting power with respect to 17,295 shares of common stock (comprised of 1,426 shares of Class A Common Stock and 15,869 shares of Class B Common Stock), shared voting power with respect to 3,099,722 shares of common stock (comprised of 1,133,635 shares of Class A Common Stock and 1,966,087 shares of Class B Common Stock), sole dispositive power with respect to 17,295 shares of common stock (comprised of 1,426 shares of Class A Common Stock and 15,869 shares of Class B Common Stock), and shared dispositive power with respect to 3,099,722 shares of common stock (comprised of 1,133,635 shares of Class A Common stock and 1,966,087 shares of Class B Common Stock).

(8) The Gale IRA may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 342 shares of common stock (comprised of 29 shares of Class A Common Stock and 313 shares of Class B Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 342 shares of common stock (comprised of 29 shares of Class A Common Stock and 313 shares of Class B Common Stock).

(9) Puffin Partners may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 957,000 shares of common stock (comprised of 957,000 shares of Class A Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 957,000 shares of common stock (comprised of 957,000 shares of Class A Common Stock).

(10) Puffin GP may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 957,000 shares of common stock (comprised of 957,000 shares of Class A Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 957,000 shares of common stock (comprised of 957,000 shares of Class A Common Stock).

(11) Montrose LP may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 143,000 shares of common stock (comprised of 143,000 shares of Class A Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 143,000 shares of common stock (comprised of 143,000 shares of Class A Common Stock).

(12) Montrose GP may be deemed to have sole voting power with respect to 0 shares of common stock, shared voting power with respect to 143,000 shares of common stock (comprised of 143,000 shares of Class A Common Stock), sole dispositive power with respect to 0 shares of common stock, and shared dispositive power with respect to 143,000 shares of common stock (comprised of 143,000 shares of Class A Common Stock).

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(c) The information provided in Item 4 above is hereby incorporated by reference.

(d) The right to receive dividends from, and proceeds from the sale of, the shares of Class A Common Stock and Class B Common Stock held of record and/or beneficially owned by Puffin Partners, Puffin GP, Montrose LP, and Montrose GP is governed by their respective limited partnership agreements and limited liability regulations, as applicable, of each of such entities, and such dividends or proceeds may be distributed with respect to numerous general and limited partnership or membership interests.

The right to receive dividends from, and proceeds from the sale of, the shares of Class A Common Stock and Class B Common Stock held of record and/or beneficially owned by the Estate is governed by will, testamentary and testate law.

(e) Not applicable.

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF THE ISSUER.

The information set forth in Item 2, Item 3 and Item 5 is hereby incorporated by reference in its entirety.

Each of Mr. Rose, the Estate, Mr. Gale, the Gale IRA, the 2001 Trust and the 2002 Trust signed a Lock-Up Agreement, as extended by that certain Lock-up Extension (the “Lock-Up Agreements”), in the forms attached as exhibits hereto, pursuant to which such person or entity agreed with the underwriters in the IPO, on behalf of itself and its affiliates, for a period of 180 days following May 25, 2016, subject to certain exceptions, it and they will not, directly or indirectly, offer, sell, contract to sell, pledge, grant any option to purchase, make any short sale, or otherwise dispose of or hedge any of the Issuer’s shares of common stock, any options or warrants to purchase any shares of the Issuer’s common stock, or any securities convertible into, or exchangeable for or that represent the right to receive shares of the Issuer’s common stock. Citigroup Global Markets Inc. and Cowen and Company, LLC, on behalf of the underwriters, may, in their sole discretion, at any time without prior notice, release all or any portion of the shares from the restrictions in any such agreement. Each of the Reporting Persons is subject to the provisions of the Lock-Up Agreements.

Cardinal Investment Company, Inc., an affiliate of the Reporting Persons, is a party to that certain Seventh Amended and Restated Registration Rights Agreement dated as of November 10, 2010 (the “Registration Rights Agreement”), pursuant to which holders of more than 67% of the registerable shares of the Issuer, at any time at least six months after the completion of the IPO, may twice request that the Issuer effect the registration of at least 50% of the registerable shares held by all holders of registration rights, or a lesser number of shares if the aggregate price to the public of the offering (net of underwriter discounts) will be at least $5 million. Furthermore, if Form S-3 is available for an offering by the initiating holders, the initiating holders may request that the Issuer effect an unlimited number of registrations on Form S-3 at an aggregate offering price of at least $1,000,000 per registration on Form S-3. In addition, the holders of registrable securities have piggyback registration rights if the Issuer determines to register any equity securities for its own account or the account of another security holder (other than in the IPO). The Issuer will pay the registration expenses, other than underwriting fees, discounts or commissions, of the shares registered pursuant to the registrations described above, but limited to four registrations on Form S-3. The Registration Rights Agreement terminates with respect to any holder who is permitted to sell, within a 90-day period, all of such holder’s registrable shares in compliance with Rule 144.

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To the Reporting Persons’ knowledge, there are no other contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2 and between such persons and any person with respect to any securities of the Issuer.

The descriptions contained in this Statement on Schedule 13D of the Lock-Up Agreements and the Registration Rights Agreement are summaries only and are qualified in their entireties by the actual terms of each such agreement, which are incorporated herein by this reference. See Item 7 “Material to be Filed as Exhibits.”

ITEM 7. MATERIAL TO BE FILED AS EXHIBITS.

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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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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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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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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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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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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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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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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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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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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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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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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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