Munich Re has had to provide another $1.6bn of reserves into its US subsidiary American Re, reports say.
Despite this, the group said it was still confident of hitting its 12% after-tax return on equity target for the year.
Munich Re's US venture has cost it $7.3bn in total but Nikolaus Von Bomhard, Munich Re's chief executive, said he was convinced it "was the right strategic decision".
The need for additions to reserves was now "resolved", Bomhard said. "There is no more uncertainty," he added.
Credit analysts remained cautious. Standard & Poor's confirmed its A+ rating with a stable outlook but said: "The announced reserve addition is a setback in terms of our earnings expectations and, in our view, the risk of further reserve increases remains."
AM Best put Munich Re on review with negative implications last week.