Material Event (Form 8-K)

On June 2, 2026, Northern Oil and Gas, Inc., a Delaware corporation (the "Company"), filed a prospectus supplement (the "Resale Prospectus Supplement") to the prospectus contained in its effective Registration Statement on Form S-3ASR (File No. 333-296399) covering the resale of up to 3,689,413 shares of the Company's common stock, par value $0.001 per share ("Common Stock"), which may be used by the selling stockholder identified therein to resell shares of Common Stock received by the selling stockholder in connection with the transactions (the "Parallax Acquisition") contemplated by that certain asset purchase and sale agreement, dated May 22, 2026 (the "PSA"), among Parallax Energy Operating Inc., a corporation existing under the laws of the Province of Alberta ("Seller"), NOG Energy Canada, Ltd., a corporation existing under the laws of the Province of Alberta and a wholly owned subsidiary of the Company, and, for certain limited purposes, the Company. Pursuant to the terms of the PSA, at the closing of the Parallax Acquisition, the Company and Seller entered into a registration rights agreement, pursuant to which, among other things and subject to certain restrictions, the Company agreed to file with the Securities and Exchange Commission a prospectus supplement registering for resale the shares of Common Stock issued to Seller (or its permitted transferees) upon consummation of the Parallax Acquisition.

The Company is filing this Current Report on Form 8-K to provide the legal opinion as to the validity of the shares of Common Stock covered by the Resale Prospectus Supplement, which opinion is attached hereto as Exhibit 5.1 and is incorporated herein by reference.