Munich Re's financial strength has been called into question after Fitch Ratings downgraded the German reinsurer.
Fitch expressed concern over the group's ability to outperform the underwriting market over the long-term.
The rating action saw Munich's insurer financial strength rating (IFS) and long-term issuer rating downgraded to 'AA+' from 'AAA'. However Fitch has removed the ratings from Watch Negative and the outlook is now stable.
A Fitch spokesman said: "The agency believes the capital strength of Munich Re is strong but has reduced substantially during this year. The group's investments in Allianz AG and Hypovereinsbank fell in value by more than 65% during the first three-quarters of this year.
"As a result the group's valuation reserves have declined significantly."
Munich Re's strong remedial action over the past two years has enabled it to achieve a combined ratio of 102%. Fitch said this would place Munich strongly for future growth.