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): August 23, 2023 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 August 23, 2023, RLI Corp. issued a press release reporting its estimated pretax catastrophe losses attributable to Hawaiian wildfires. Furnished as Exhibit 99.1 and incorporated herein by reference is the press release issued by RLI Corp. ​ Item 9.01              Financial Statements and Exhibits. ​ (d) Exhibits ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press Release dated August 23, 2023. 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: August 23, 2023 By: /s/ Jeffrey D. Fick ​ ​ Jeffrey D. Fick ​ Chief Legal Officer & Corporate Secretary ​ ​ ​