UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of report (Date of earliest event reported): July 19, 2013

RED MOUNTAIN RESOURCES, INC.

(Exact name of registrant as specified in its charter)

(214) 871-0400

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 1.01 Entry into a Material Definitive Agreement.

Underwriting Agreement

On July 23, 2013, Red Mountain Resources, Inc. (the “Company”) entered into an Underwriting Agreement (the “Underwriting Agreement”) with Global Hunter Securities, LLC, as representative of the several underwriters named therein (collectively, the “Underwriters”), pursuant to which the Company will sell to the public and to certain noteholders in cancellation of up to $4.3 million of indebtedness through the Underwriters on a best efforts basis up to 500,000 units (the “Units”), with each unit consisting of one share of 10.0% Series A Cumulative Redeemable Preferred Stock, par value $0.0001 per share and liquidation preference of $25.00 per share (“Series A Preferred Stock”), and one warrant with each warrant entitling the purchaser to purchase up to 25 shares of the Company’s common stock (the “Warrants”), at a public offering price of $22.50 per Unit (such offering, the “Offering”).

The Units will not be issued or certificated. The shares of Series A Preferred Stock and the Warrants are immediately separable and will be issued separately, but will be purchased together as a Unit in the Offering. The offer and sale of the Series A Preferred Stock and the Warrants were registered with the Securities and Exchange Commission (the “Commission”) pursuant to a Registration Statement on Form S-3 (File No. 333-186076), which became effective on February 1, 2013, and the initial closing is expected to occur on or about July 26, 2013. The Offering may be consummated in more than one closing.

Assuming the sale of all of the Units, the Company intends to use the net proceeds from the Offering of approximately $6.2 million (after deducting the underwriting discounts and commissions and estimated offering expenses) for general corporate purposes, including to fund a portion of its 2014 drilling and development program and the payment of approximately $0.6 million of accrued interest and fees on the indebtedness to be cancelled in a concurrent offering.

Some of the Underwriters and their affiliates have performed investment and commercial banking and advisory services for the Company and its affiliates from time to time for which they have received customary fees and expenses. The Underwriters and their affiliates may, from time to time, engage in transactions with and perform services for the Company in the ordinary course of their business.

The Underwriting Agreement contains customary representations, warranties, covenants, conditions to closing, termination provisions, indemnification and other obligations of and agreements by the parties. The foregoing description of the Underwriting Agreement is qualified in its entirety by reference to such Underwriting Agreement, a copy of which is filed herewith as Exhibit 1.1 and is incorporated herein by reference.

Warrant Agreement

In connection with the Offering, the Company will enter into a Warrant Agreement (the “Warrant Agreement”) with Broadridge Corporate Issuer Solutions, Inc. to serve as warrant agent with respect to the Warrants. The Warrants will have an exercise price of $1.00 per share and be exercisable beginning on the date of issuance and may be exercised until the earlier of (i) the date that is three years after the date of issuance, or (ii) the first Trading Day (as defined in the Warrant Agreement) that is at least 30 days after the date that the Company has provided notice to the holders of the Warrants by filing a Current Report on Form 8-K with the Commission stating that the Company’s common stock has (A) achieved a 20 Trading Day VWAP (as defined in the Warrant Agreement) of $1.50 per share (the “Trigger Price”) or more and (B) traded, in the aggregate, 3,000,000 shares (the “Trigger Volume”) or more over the same 20 consecutive Trading Days for which the 20 Trading Day VWAP was calculated; provided, that clause (ii) shall only be applicable so long as a Warrant is exercisable for shares of the Company’s common stock.

The exercise price, number of shares issuable upon exercise, Trigger Price and Trigger Volume are subject to appropriate adjustment in the event of stock dividends, stock splits, stock consolidations, combinations, reverse stock splits, reclassifications and similar events affecting the Company’s common stock.

The foregoing description of the Warrant Agreement is qualified in its entirety by reference to such Warrant Agreement, a copy of which is filed herewith as Exhibit 4.3 and is incorporated herein by reference.

Amendment to Credit Agreement

On July 19, 2013, the Company entered into an amendment and consent (the “Amendment”) to the Senior First Lien Secured Credit Agreement, dated February 5, 2013 (the “Credit Agreement”), with Cross Border Resources, Inc. (“Cross Border”), Black Rock Capital, Inc. (“Black Rock”) and RMR Operating, LLC (“RMR Operating”), as borrowers, and Independent Bank, as lender (“Lender”). Each of Cross Border, Black Rock and RMR Operating are subsidiaries of the Company. Pursuant to the Amendment, (i) the Credit Agreement is amended to permit the payment of cash dividends on the Series A Preferred Stock so long as the Company is not otherwise in default under the Credit Agreement and payment of such cash dividends would not cause the Company to be in default under the Credit Agreement and (ii) Lender consents to the repayment of certain of the Company’s outstanding indebtedness from the proceeds of the Offering.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant

Reference is made to the discussions in Item 1.01 above under the heading “Underwriting Agreement” and Item 5.03 below with respect to the issuance of the Series A Preferred Stock and the obligation of the Company to redeem the shares of Series A Preferred Stock on July 15, 2018, which discussions are incorporated herein by reference.

Item 3.03 Material Modification to Rights of Security Holders.

The matters described in Item 5.03 below are incorporated herein by reference.

Item 5.03 Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.

In connection with the Offering, the Company’s board of directors approved Articles of Amendment to the Company’s Articles of Incorporation (the “Articles of Amendment”) that set forth the designations, preferences and rights of the Series A Preferred Stock, which was filed with the Secretary of State of the State of Florida on July 23, 2013. The designations, rights and preferences of the Series A Preferred Stock include the following:

The foregoing description does not purport to be complete and is qualified in its entirety by reference to the Articles of Amendment, which is filed as Exhibit 3.1 hereto and incorporated herein by reference.

Item 8.01 Other Events.

The legal opinion and consent of Akin, Gump, Strauss, Hauer & Feld, L.L.P. relating to the issuance and sale of the Warrants is attached as Exhibit 5.1 hereto. The legal opinion and consent of Carlton Fields, P.A. relating to the issuance and sale of the Series A Preferred Stock and the shares of common stock underlying the Warrants is attached as Exhibit 5.2 hereto.

Item 9.01 Financial Statements and Exhibits.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized.

EXHIBIT INDEX