Both Fitch Ratings and Standard & Poor’s Ratings Services have affirmed the ratings of RenaissanceRe, after the Bermuda reinsurer announced its proposed $1.9 billion acquisition of Platinum Underwriters Holdings, Ltd.

The two agencies’ assessments run counter to that of AM Best, which earlier this week put RenRe’s ratings under review with negative implications.

Both Fitch and S&P affirmed their ratings for RenRe, which include an A+ financial strength rating from both agencies, with a stable outlook.

Fitch said it viewed the Platinum deal as “a slight credit negative to RNR in the near term given the execution and integration risk inherent in an acquisition. Successful execution of this acquisition could provide longer term positive credit benefits relating to diversification of earnings and business profile.”

Fitch said RenRe had responded to “stressful reinsurance market conditions” by reducing its risk exposures.The market conditions had hit Platinum harder, Fitch said, as it was a smaller reinsurer, whose net premiums had shrunk by 45 percent between 2008 and 2013.

Platinum had shifted its business mix away from property and marine business and into casualty and specialty reinsurance business.

“As such, Fitch favourably views the addition of PTP as marginally diversifying RNR away from its property catastrophe business that should help the company to reduce earnings and cash flow exposure to cyclical conditions in the property catastrophe market,” the agency commented.

While complicfations could arise from the integration of Platinum, Fitch said integration risk was mitigated by the fact the two companies write similar lines of business and that Platinum was “unencumbered by legacy issues as the company was formed relatively recently in 2002”.

S&P sees value for RenRe in the combination and sees limited integration risks.

“The integration risk of the acquisition is mitigated by the relative simplicity of Platinum’s organizational structure based on both legal entities and office locations, and the ease with which RenaissanceRe will be able to assimilate Platinum’s property catastrophe portfolio onto its platform,” S&P stated.

“Successful execution will accelerate the progress of RenaissanceRe’s expansion into specialty and casualty reinsurance with the addition Platinum’s profitable book of diversifying business.”

S&P also put Platinum’s A- financial strength rating on CreditWatch [under review] with positive implications, based on “the potential support it will receive as an important part of RenaissanceRe’s specialty strategy and the overall RenaissanceRe group”.

S&P said Platinum’s historically profitable casualty book would contribute meaningfully to RenaissanceRe’s profits.