The Moody's agency has changed its rating outlook of the Swiss Reinsurance company and its subsidiaries to negative from stable.
In a statement from London, Moody's said that the decision was as much a reflection of company-specific factors as of powerful market forces affecting all industry participants.
"The change in outlook reflects mounting evidence that market and shareholder pressures are driving Swiss Re to take a comparatively aggressive stance in capital management, acquisitions and business development," the statement said.
However, Moody's said it still viewed Swiss Re as one of the strongest reinsurers in the world.
"The breadth and depth of the organisation's intellectual and financial resources is only comparable to that of a handful of peers," the statement said
"Further, Moody's expects Swiss Re will continue to be a superior performer, to continue to benefit from consolidation, to be instrumental and a key player in the world of risk identification, management and financing, and expects that its financial strength will continue to surpass that of most of its peers," it added.
swissinfo with agencies