Results of Operations · Reg FD Disclosure

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): April 28, 2026 __________________________________________ First Busey Corporation (Exact name of Registrant as specified in its charter) __________________________________________ Nevada 0-15950 37-1078406 (State of Incorporation) (Commission File Number) (I.R.S. Employer Identification No.) 11440 Tomahawk Creek Parkway Leawood , Kansas 66211 (Address of Principal Executive Offices) (217) 365-4544 (Registrant’s telephone number, including area code) N/A (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: ☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, $0.001 par value BUSE Nasdaq Stock Market LLC Depositary Shares, each representing a 1/40th interest in a share of 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock , $0.001 par value BUSEP Nasdaq Stock Market LLC Indicate by check mark whether the Registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ☐ If an emerging growth company, indicate by check mark if the Registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ Item 2.02    Results of Operations and Financial Condition. On April 28, 2026, First Busey Corporation (“Busey”) issued a press release (“Earnings Release”) disclosing financial results for the quarter ended March 31, 2026. A copy of the Earnings Release is attached hereto as Exhibit 99.1 and is incorporated herein by reference. The information in Item 2.02 of this Current Report on Form 8-K and Exhibit 99.1 attached hereto is being “furnished” and will not, except to the extent required by applicable law or regulation, be deemed “filed” by Busey for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (“Exchange Act”), or otherwise subject to the liabilities of that section, nor will any of such information or exhibits be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended (“Securities Act”), or the Exchange Act. Item 7.01    Regulation FD Disclosure. On April 28, 2026, Busey published its Earnings Investor Presentation discussing financial results for the quarter ended March 31, 2026. A copy is attached hereto as Exhibit 99.2 and is incorporated herein by reference. The information in Item 7.01 of this Current Report on Form 8-K and Exhibit 99.2 attached hereto is being “furnished” and will not, except to the extent required by applicable law or regulation, be deemed “filed” by Busey for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor will any of such information or exhibits be deemed incorporated by reference into any filing under the Securities Act or the Exchange Act. Item 9.01.    Financial Statements and Exhibits. Exhibit Number Description of Exhibit 99.1 Earnings Release issued by First Busey Corporation, dated April 28, 2026 99.2 Earnings Investor Presentation issued by First Busey Corporation, dated April 28, 2026 104 Cover Page Interactive Data File (embedded within the Inline XBRL document and included in Exhibit 101) 2 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, thereunto duly authorized. FIRST BUSEY CORPORATION Date: April 28, 2026 By: /s/ CHRISTOPHER H.M. CHAN Christopher H.M. Chan Executive Vice President, Chief Financial Officer 3