Other Events. On August 6, 2026 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 17.5 cents per share on its common stock. The dividend will be paid September 18, 2026 to shareholders of record on September 4, 2026. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Director — Gary S. Gladstein: The filing concerns the planned retirement of a Board Director, which is a governance matter rather than a senior executive management departure.

Results of Operations and Financial Condition. On July 21, 2026, the Registrant issued a press release announcing earnings for the quarter ended June 27, 2026. A copy of the press release announcing the second quarter 2026 earnings is attached as Exhibit 99.1.

Other Events. On May 8, 2026 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 35 cents per share on its common stock. The dividend will be paid June 19, 2026 to shareholders of record on June 5, 2026. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On April 21, 2026, the Registrant issued a press release announcing earnings for the quarter ended March 28, 2026. A copy of the press release announcing the first quarter 2026 earnings is attached as Exhibit 99.1.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant The information described above under

Entry into a Material Definitive Agreement On March 27, 2026, Mueller Industries, Inc. (the “Company”) entered into a Credit Agreement (the “Credit Agreement”) among the Company (as borrower) and Bank of America, N.A. (“Bank of America”) (as administrative agent, lender, swing line lender and letter of credit issuer). The Credit Agreement replaces the Company's prior credit agreement among the Company (as borrower), Bank of America (as administrative agent) and certain lenders (including Bank…

Other Events. On February 19, 2026 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 35 cents per share on its common stock. The dividend will be paid March 27, 2026 to shareholders of record on March 13, 2026. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On February 3, 2026 , the Registrant issued a press release announcing earnings for the quarter and year ended December 27, 2025. A copy of the press release announcing the fourth quarter and fiscal 2025 earnings is attached as Exhibit 99.1.

Other Events. On November 7, 2025 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 25 cents per share on its common stock. The dividend will be paid December 19, 2025 to shareholders of record on December 5, 2025. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On October 21, 2025, the Registrant issued a press release announcing earnings for the quarter ended September 27, 2025. A copy of the press release announcing the third quarter 2025 earnings is attached as Exhibit 99.1.

Other Events. On July 31, 2025 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 25 cents per share on its common stock. The dividend will be paid September 19, 2025 to shareholders of record on September 5, 2025. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On July 22, 2025, the Registrant issued a press release announcing earnings for the quarter ended June 28, 2025. A copy of the press release announcing the second quarter 2025 earnings is attached as Exhibit 99.1.

Chief Manufacturing Officer — Steffen Sigloch: The executive is transitioning to an internal advisory role rather than leaving the company entirely, indicating an orderly internal realignment rather than a loss of personnel.

Other Events. On May 9, 2025, the Company issued a press release announcing that its Board of Directors has declared a regular quarterly cash dividend on its common stock of 25 cents per share. The dividend will be payable June 20, 2025, to shareholders of record on June 6, 2025. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On April 22, 2025, the Registrant issued a press release announcing earnings for the quarter ended March 29, 2025. A copy of the press release announcing the first quarter 2025 earnings is attached as Exhibit 99.1.

Other Events. On February 21, 2025 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 25 cents per share on its common stock. The dividend will be paid March 28, 2025 to shareholders of record on March 14, 2025. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On February 4, 2025 , the Registrant issued a press release announcing earnings for the quarter and year ended December 28, 2024. A copy of the press release announcing the fourth quarter and fiscal 2024 earnings is attached as Exhibit 99.1.

Other Events. On November 8, 2024 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 20 cents per share on its common stock. The dividend will be paid December 20, 2024 to shareholders of record on December 6, 2024. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On October 22, 2024, the Registrant issued a press release announcing earnings for the quarter ended September 28, 2024. A copy of the press release announcing the third quarter 2024 earnings is attached as Exhibit 99.1.

Other Events. On August 1, 2024 the Registrant issued a press release announcing that its Board has declared a regular quarterly cash dividend of 20 cents per share on its common stock. The dividend will be paid September 20, 2024 to shareholders of record on September 6, 2024. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On July 23, 2024, the Registrant issued a press release announcing earnings for the quarter ended June 29, 2024. A copy of the press release announcing the second quarter 2024 earnings is attached as Exhibit 99.1.

The filing describes the approval of a stock incentive plan, which is a compensatory arrangement rather than a change in management personnel.

Other Events. On May 10, 2024, the Company issued a press release announcing that its Board of Directors has declared a regular quarterly cash dividend on its common stock of 20 cents per share. The dividend will be payable June 21, 2024, to shareholders of record on June 7, 2024. A copy of the press release announcing the payment and record dates is attached as Exhibit 99.1.

Results of Operations and Financial Condition. On April 23, 2024, the Registrant issued a press release announcing earnings for the quarter ended March 30, 2024. A copy of the press release announcing the first quarter 2024 earnings is attached as Exhibit 99.1.