Fitch Ratings has upgraded Bermudian-based PartnerRe Ltd following its recent acquisition by Covéa Cooperations SA, the French mutual insurer.

Covéa acquired PartnerRe from EXOR NV for total cash consideration of $9.1 billion.

Fitch upgraded PartnerRe's issuer default rating to 'A' from 'A-' and senior unsecured debt ratings to 'A-' from 'BBB+'.

The ratings agency also upgraded the insurer financial strength rating of Partner Reinsurance Company Ltd, the company's principal reinsurance operating subsidiary, to 'AA-' (Very Strong) from 'A+' (Strong), and removed all ratings from Rating Watch Positive.

The rating outlook is stable. The upgrade reflects a one-notch ratings uplift due to the change in ownership to Covéa.

Fitch said it does not maintain public ratings on Covéa but does internally monitor the company's consolidated credit quality, which Fitch considers to be superior to PartnerRe's stand-alone 'A+' IFS assessment.

As such, ownership by Covéa, a larger property/casualty, health and life insurance organisation, benefits PartnerRe's ratings under a group credit approach.

Fitch viewed EXOR's ownership as neutral to PartnerRe's ratings and as less strategic than the new ownership by Covéa.

Fitch views PartnerRe's strategic importance to Covéa as "very important" per Fitch's group rating methodology as PartnerRe's size makes it a significant addition to Covéa with potential synergies with the larger insurance group as a whole.

Furthermore, this assessment could improve to "core" after a period of seasoning under Covéa ownership.

PartnerRe provides Covéa diversification outside of France, as Covéa maintains a leading market position in French p/c, but has minimal global reinsurance business.

PartnerRe writes a diverse international mix of property, casualty, speciality, and life and health reinsurance products.

Fitch expects Covéa to offer reasonable support to PartnerRe as needed and to conservatively manage the reinsurers' capitalisation. Fitch also expects PartnerRe to continue to manage its operations generally independent of Covéa, as PartnerRe had done under EXOR ownership.