OREANDA-NEWS. A.M. Best has affirmed the financial strength rating of A (Excellent) and the issuer credit rating of “a+” of MS Frontier Reinsurance Limited (MS Frontier) (Hamilton, Bermuda). The outlook for each rating is stable. MS Frontier is a wholly owned subsidiary of Mitsui Sumitomo Insurance Company, Limited (MSI), which is a subsidiary of MS&AD Insurance Group Holdings, Inc. (MS&AD).