Following Liberty Mutual's $6.1 billion acquisition of Safeco Corporation, A.M. Best has downgraded the issuer credit rating (ICR) of Safeco to align the ratings with Liberty Mutual.

The issuer credit rating of Safeco was lowered to "bbb" from "bbb-plus," and the ICR of Safeco Insurance Companies and its members were lowered to "a" from "a-plus." The outlook for all ratings is stable, Oldwick, N.J.-based Best said.

The financial strength rating (FSR) of Safeco remains "A," also in line with Liberty Mutual.

Best said the acquired Safeco entities will be integrated into the Liberty Insurance Holdings (LIH) pool over the near term. "[Liberty Mutual Group Inc.] has integrated a number of similar transactions over the years, and as in the past, A.M. Best will monitor the progress of this integration going forward."

Best analyst Gordon McLean said, "We lowered [Safeco's] ICR; we maintained the [FSR], so at this point, the ratings are equivalent to Liberty's ratings...because going forward, it's going to be integrated into one of Liberty's pools."

He added that Safeco's FSR had been "A" before the acquisition, but Best had subsequently revised the positive outlook to stable to align it with Liberty Mutual.