OLDWICK, N.J., October 26, 2023 AM Best has upgraded the Financial Strength Rating to A (Excellent) from A- (Excellent) and the Long-Term Issuer Credit Ratings to "a" (Excellent) from "a-" (Excellent) of Pennsylvania National Mutual Casualty Insurance Company (Penn Mutual), its subsidiaries, Penn National Security Insurance Company and Founders Insurance Company, and its mutual company affiliate, Partners Mutual Insurance Company (Waukesha, WI), collectively referred to as Penn National Insuran