OLDWICK, N.J.–(BUSINESS WIRE)–A.M. Best has affirmed the Long-Term Issuer Credit Rating (Long-Term ICR) of “a-” of W. R. Berkley Corporation (W. R. Berkley) (Greenwich, CT) [NYSE:WRB]. Concurrently, A.M. Best has affirmed the Financial Strength Rating (FSR) of A+ (Superior) and the Long-Term ICRs of “aa-” of Berkley Insurance Company (BIC) (Wilmington, DE) and most of its reinsured subsidiaries and affiliates, collectively referred to as W. R. Berkley Insurance Group (the Berkley Group). A.M.