Results of Operations

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): July 24, 2018    MUELLER INDUSTRIES, INC. (Exact name of registrant as specified in its charter)       Delaware   1-6770   25-0790410 (State or other (Commission File (IRS Employer jurisdiction of Number) Identification No.) incorporation)        8285 Tournament Drive, Suite 150   Memphis, Tennessee 38125 (Address of principal executive offices) (Zip Code) Registrant’s telephone number, including area code:    (901) 753-3200 Registrant’s Former Name or Address, if changed since last report:   N/A   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 (see General Instruction A.2. below): ☐ 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))     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 of revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐   Item 2.02. Results of Operations and Financial Condition. On  July 24, 2018 , the Registrant issued a press release announcing earnings for the quarter ended  June 30, 2018 . A copy of the press release announcing the  second quarter  2018 earnings is attached as Exhibit 99.1. Item 9.01. Financial Statements and Exhibits.   (d) Exhibits     99.1 Press release, dated July 24, 2018 reporting second quarter 2018 earnings.                                   2   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.     MUELLER INDUSTRIES, INC.       By: / s/   JEFFREY A. MARTIN     Name: Jeffrey A. Martin   Title: Chief Financial Officer and Treasurer       July 24, 2018         3 Exhibit Index   Exhibit No. Description      99.1 Press release, dated July 24, 2018.                                     4