Other Events. ​ On August 13, 2026, RLI Corp. (“RLI”) a nnounced that its Board of Directors approved a regular quarterly dividend on its common stock of $0.18 per share. The dividend is payable on September 15, 2026 to shareholders of record as of August 31, 2026. ​ Furnished as Exhibit 99.1 and incorporated herein by reference is a copy of the press release issued by RLI announcing the dividend. ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: July 22, 2026 By: /s/ Aaron P. Diefenthaler ​ ​ Aaron P. Diefenthaler ​ Chief Financia…

Director — James H. Bradshaw: Appointment of a new independent director to the Board and specific committees.

Director — Michael Angelina: Mr. Angelina resigned to explore joining the Board of Directors of another insurance company.

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”). Re…

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: April 22, 2026 By: /s/ Aaron P. Diefenthaler ​ ​ Aaron P. Diefenthaler ​ Chief Financi…

Entry into a Material Definitive Agreement. Senior Notes Offering On March 3, 2026, RLI Corp. (the “Company”) completed the public offering of $300 million in aggregate principal amount of its 5.375% Senior Notes due 2036 (the “Notes”). The Notes were issued pursuant to an indenture entered into on March 3, 2026 (the “Base Indenture”), as supplemented by a first supplemental indenture entered into on March 3, 2026 (the “First Supplemental Indenture”), in each case, between the Company and Com…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. ​ The information set forth under

Other Events. ​ On February 18, 2026, RLI Corp. (“RLI”) a nnounced that its Board of Directors approved a regular quarterly dividend on its common stock of $0.16 per share. The dividends is payable on March 16, 2026 to shareholders of records as of March 2, 2026. ​ Furnished as Exhibit 99.1 and incorporated herein by reference is a copy of the press release issued by RLI announcing the dividend. ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: January 21, 2026 By: /s/ Aaron P. Diefenthaler ​ ​ Aaron P. Diefenthaler ​ Chief Finan…

CFO — Todd W. Bryant: The CFO is retiring with a named internal successor (Aaron P. Diefenthaler) already appointed, indicating an orderly succession rather than a sudden loss of leadership.

Other Events. ​ On November 13, 2025, 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 $0.16 per share. Both dividends are payable on December 19, 2025 to shareholders of records as of November 28, 2025. ​ Furnished as Exhibit 99.1 and incorporated herein by reference is a copy of the press release issued by RLI announcing the dividend. ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: October 20, 2025 By: /s/ Todd W. Bryant ​ ​ Todd W. Bryant ​ Chief Financial Officer ​…

Other Events. ​ On August 14, 2025, RLI Corp. (“RLI”) announced that its Board of Directors approved a regular quarterly dividend on its common stock of $0.16 per share. The dividend is payable on September 19, 2025 to shareholders of record as of August 29, 2025. ​ Furnished as Exhibit 99.1 and incorporated herein by reference is a copy of the press release issued by RLI announcing the dividend. ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: July 21, 2025 By: /s/ Todd W. Bryant ​ ​ Todd W. Bryant ​ Chief Financial Officer ​ ​ ​

Other Events. ​ On May 13, 2025, RLI Corp. (“RLI”) announced that its Board of Directors approved a regular quarterly dividend on its common stock of $0.16 per share. The dividend is payable on June 20, 2025 to shareholders of record as of May 30, 2025. ​ Furnished as Exhibit 99.1 and incorporated herein by reference is a copy of the press release issued by RLI announcing the dividend. ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: April 23, 2025 By: /s/ Todd W. Bryant ​ ​ Todd W. Bryant ​ Chief Financial Officer ​ ​ ​

Other Events. ​ On February 13, 2025, RLI Corp. (“RLI”) announced that its Board of Directors approved) a regular quarterly dividend on its common stock of $0.15 per share. The dividend is payable on March 20, 2025 to shareholders of record as of February 28, 2025. ​ Furnished as Exhibit 99.1 and incorporated herein by reference is a copy of the press release issued by RLI announcing the dividend. ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: January 22, 2025 By: /s/ Todd W. Bryant ​ ​ Todd W. Bryant ​ Chief Financial Officer ​ ​ ​

Other Events. ​ On November 7, 2024, RLI Corp. (“RLI”) announced that its Board of Directors approved the following: (i) a special cash dividend on its common stock of $4.00 per share, (ii) a regular quarterly dividend on its common stock of $0.29 per share, and (iii) a two-for-one stock split of its common stock. ​ Both dividends are payable on December 20, 2024, to shareholders of record as of November 29, 2024. The two-for-one stock split is for shareholders of record as of December 31, 20…

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: October 21, 2024 By: /s/ Todd W. Bryant ​ ​ Todd W. Bryant ​ Chief Financial Officer ​ ​ ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: July 22, 2024 By: /s/ Todd W. Bryant ​ ​ Todd W. Bryant ​ Chief Financial Officer ​ ​ ​

hereof and should not be deemed to be “filed” under the Securities Exchange Act of 1934. 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: April 22, 2024 By: /s/ Todd W. Bryant ​ ​ Todd W. Bryant ​ Chief Financial Officer ​ ​ ​