13D Filing: Leucadia National and Fiesta Restaurant Group Inc. (FRGI)

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

Under the Securities Exchange Act of 1934

(Amendment No. 2)

Fiesta
Restaurant Group, Inc.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

31660B101

(CUSIP Number)

Roland T. Kelly

11100 Santa Monica Boulevard, 11th Floor

Los Angeles, CA 90025

Tel: (310) 914-1373

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

August 30, 2017

(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.  ☐

This Amendment No. 2 amends the Statement on Schedule 13D first filed by Leucadia National Corporation
(Leucadia) on behalf of itself and its controlled subsidiaries (the Reporting Person) with the Securities and Exchange Commission on June 19, 2017 and Amendment No. 1 filed on August 18, 2017
relating to the Common Stock, par value $0.01 per share (the Common Stock), of Fiesta Restaurant Group, Inc., a Delaware corporation (the Issuer). The principal executive offices of the Issuer are located
at 14800 Landmark Boulevard, Suite 500, Dallas, Texas 75254. Capitalized terms used herein but not otherwise defined herein have the meanings given to them in the Schedule 13D.

Item 3. Source and Amount of Funds or Other Consideration.

From August 9, 2017 through August 30, 2017, the Reporting Person purchased an aggregate of 650,000 shares of Common Stock. The securities were
acquired by the Reporting Person using cash from working capital in the amount of approximately $11.8 million.

Item 4. Purpose of Transaction.

The Reporting Person purchased the Common Stock reported herein for investment purposes. The Reporting Person intends to purchase additional shares of
Common Stock from time to time, if, at such time, the terms of such investment are favorable to the Reporting Person and the Reporting Person deems the investment to be prudent.

Other than described above, the Reporting Person does not have any plans or proposals of the type referred to in Items 4(a) through (j) of Schedule 13D.
The Reporting Person, however, retains the right to change its intent and to pursue any transaction contemplated in Items 4(a) through (j) of Schedule 13D and, to the extent the Reporting Persons affiliates operate as broker-dealers, they
retain the right to pursue a role as a financial advisor, underwriter or placement agent with respect to any such transaction involving the Issuer and its affiliates.

Item 5. Interest in Securities of the Issuer.

Number of shares as to which the Reporting Person has:

Sole power to vote or to direct the vote: 2,006,295

Shared power to vote or to direct the vote: 0

Sole power to dispose or to direct the disposition of: 2,006,295

Shared power to dispose or to direct the disposition of: 0

During the past sixty days, the Reporting Person engaged in the following open market purchases of Common Stock:

Brian P. Friedman is the President and a director of Leucadia. Mr. Friedman has also been a director of the Issuer since April 2011. Mr. Friedman
beneficially owns an aggregate of 64,938 shares of Common Stock representing 0.2% of the Issuers outstanding shares. Mr. Friedmans beneficial ownership includes 36,270 shares of Common Stock held directly and 28,668 shares of Common
Stock held indirectly through a partnership.

Except as set forth in this Item 5, no person other than each respective record owner of the securities
referred to herein is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities.

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.