UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 or 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2025 AMPCO-PITTSBURGH CORPORATION OR (Registrant's telephone number) ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Pennsylvania 25-1117717 (State of Incorporation) For the transition period from to (I.R.S. Employer Identification No.) Commission File ...