Company Update

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): May 14, 2026 RLI Corp. (Exact name of registrant as specified in its charter) ​ ​ ​ ​ ​ ​ Delaware ​ 001-09463 ​ 37-0889946 (State or other jurisdiction ​ (Commission ​ (IRS Employer of incorporation) ​ File Number) ​ Identification No.) ​ ​ ​ ​ ​ 9025 North Lindbergh Drive , Peoria , IL ​ 61615 (Address of principal executive offices) ​ (Zip Code) ​ Registrant’s telephone number, including area code: ( 309 ) 692-1000 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: ☐ 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 Securities Exchange Act of 1934: ​ ​ ​ ​ ​ ​ Title of each class   ​ ​ ​ Trading Symbol   ​ ​ ​ Name of each exchange on which registered Common Stock $0.01 par value ​ RLI ​ New York Stock Exchange ​ 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). Emerging growth company ☐ 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 8.01 Other Events. ​ On May 14, 2026, RLI Corp. (“RLI”) a nnounced that its Board of Directors approved a special cash dividend on its common stock of $2.00 per share and a regular quarterly dividend on its common stock of $0.18 per share.  Both dividends are payable on June 12, 2026 to shareholders of record as of May 29, 2026. ​ RLI also announced its Board of Directors approved a share repurchase program authorizing an aggregate of $250 million in share repurchases (the “Repurchase Program”). Repurchases under the Repurchase Program may be made at the Company’s discretion from time to time using open market purchases or privately negotiated transactions, in accordance with applicable laws and regulations. The Repurchase Program has no expiration date. ​ Furnished as Exhibit 99.1 and incorporated herein by reference is a copy of the press release issued by RLI announcing the dividends and Repurchase Program. ​ Item 9.01 Financial Statements and Exhibits. (d) Exhibits ​ Exhibit No.   ​ ​ ​ Description ​ ​ ​ 99.1 ​ Press Release dated May 14, 2026. 104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document). ​ ​ ​ ​ ​ ​ ​ SIGNATURES 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. ​ ​ ​ ​ ​ RLI CORP. ​ ​ ​ Date: May 14, 2026 By: /s/ Jeffrey D. Fick ​ ​ Jeffrey D. Fick ​ Chief Legal Officer ​ ​ ​