☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (212) 957-5000 For the year ended September 30, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 or 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File No. 1-06620 GRIFFON CORPORATION (Exact name of registrant as specified in its charter) Delaware 11-1893410 (State or other jurisdiction (I.R.S. Employer of incorporation or organiz ...