Bel Fuse Inc.

Item 1.01. Entry into a Material Definitive Agreement Follow-on Offering On May 13, 2026, Bel Fuse, Inc. (the “Company” or “Bel”) entered into an underwriting agreement (the “Underwriting Agreement”) with Citigroup Global Markets Inc., BofA Securities, Inc. and Wells Fargo Securities, LLC as representatives (the “Representatives”) of the underwriters listed in Schedule I thereto (the “Underwriters”), pursuant to which the Company agreed to issue and sell an aggregate of 1,500,000 shares (the “Shares”) of its Class B common stock, par value $0.10 per share (“Class B Common Stock”), at a price to the public of $266.00 per share (the “Offering”). Under the terms of the Underwriting Agreement, the Company granted the Underwriters an option, for a period of 30 days after the date of the Prospectus Supplement (as defined below), to purchase up to an additional 225,000 shares of Common Stock (the “Option Shares”) at the public offering price, less underwriting discounts and commissions. Pursuant to the Underwriting Agreement, the directors and certain executive officers of the Company entered into agreements providing for a 60-day “lock-up” period with respect to sales of the Company’s securities, subject to certain exceptions. The Company estimates that the net proceeds from the Offering, after deducting underwriting discounts and commissions and estimated offering expenses, will be approximately $383.3 million. The Company intends to use the net proceeds from the Offering to pay down any outstanding indebtedness under its Credit and Security Agreement, fund the remaining 20% acquisition of Enercon Technologies, Ltd., or other acquisitions or partnership opportunities that may arise, and the remainder, if any, for general corporate purposes. The Company expects the Offering to close on May 15, 2026, subject to the satisfaction of customary closing conditions. The Company made certain customary representations, warranties and covenants concerning the Company, the registration statement and the Prospectus Supplement in the Underwriting Agreement and also agreed to indemnify the Underwriters against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the “Securities Act”). The Offering is being made pursuant to a prospectus supplement, dated May 13, 2026 (the “Prospectus Supplement”), filed with the Securities and Exchange Commission (“SEC”) on May 14, 2026 and an accompanying base prospectus that forms a part of the registration statement on Form S-3ASR (File No. 333-295813), as amended, filed with the SEC on May 12, 2026, which was effective upon filing with the SEC. This Current Report on Form 8-K does not constitute an offer to sell or a solicitation of an offer to buy any of the Shares or the Option Shares. The foregoing description of the Underwriting Agreement does not purport to be complete descriptions of the rights and obligations of the parties thereunder, and is qualified in its entirety by reference to the full text of the Underwriting Agreement that is filed as Exhibit 1.1 to this Current Report on Form 8-K, respectively, and is incorporated by reference herein. A copy of the opinion of Lowenstein Sandler LLP, relating to the validity of the Shares and the Option Shares in connection with the Offering, is filed as Exhibit 5.1 to this Current Report on Form 8-K. Item 8.01. Other Events. On May 12, 2026 and May 13, 2026, the Company issued press releases announcing the launch and pricing of the Offering, which are attached hereto as Exhibits 99.1 and 99.2, respectively. Cautionary Note Regarding Forward Looking Statements This Current Report on Form 8-K contains forward-looking statements that involve estimates, assumptions, risks and uncertainties. Forward-looking statements include, but are not limited to, statements related to the amount of proceeds expected from the Offering, the timing and certainty of completion of the Offering. The risks and uncertainties relating to the Company and the Offering include general market conditions, the Company’s ability to complete the Offering on favorable terms, or at all, as well as other risks detailed from time to time in the Company’s filings with the SEC, including in its Annual Report on Form 10-K for the year ended December 31, 2025 and in its Quarterly Report on Form 10-Q for the quarter ended March 31, 2026, and the Prospectus Supplement. These documents contain important factors that could cause actual results to differ from current expectations and from the forward-looking statements contained in this Current Report on Form 8-K. These forward-looking statements speak only as of the date of this Current Report on Form 8-K and the Company undertakes no obligation to publicly update any forward-looking statements to reflect new information, events or circumstances after the date of this Current Report on Form 8-K.