United States Securities and Exchange Commission Washington, D.C. 20549 Form 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934. For the fiscal year ended December 31, 2018. ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934. For the transition period from _____________________ to _____________________. Commission file number 000-04604 Cincinnati Financial Corporation (Exact name of registrant as specified in its charter) Ohio ...