"This issue at Swiss Re is probably not the tip of the iceberg for reinsurers but rather is an individual case," Elke Koenig told reporters on the margins of an insurance industry conference.
On Monday Swiss Re, the world's biggest reinsurer, announced a 1.2 billion Swiss franc ($1.07 billion) write-down related to credit default swaps giving protection on portfolios mostly of mortgage-backed securities. This also knocked shares of other banking and insurance heavyweights.
Primary insurers avoided investing in mortgage-backed securities because they typically did not have a fixed maturity, making it difficult for insurers to match asset duration to liability duration, Koenig said.
Hannover Re was not involved in the sort of credit reinsurance business that created problems at Swiss Re, she said. The world's fourth-biggest reinsurer was sticking to its previous estimates of possible losses due to the fallout from the subprime crisis in the United States, she added.
The company has assumed a maximum write-down of 10 million euros ($14.8 million), on its approximately 40 million euro exposure to the market for risky U.S. mortgages.
"We've conservatively valued our holdings and because we are holding the paper to maturity, I am relaxed about it," she said.
The company was keeping a close watch on its risks in the Directors' & Officers' insurance segment stemming from the credit market woes but saw no big problems for now, particularly because it had already reduced its portfolio in that segment.
European insurance regulators are preparing a set of improved risk-management rules called Solvency II which are expected to come into effect in 2012.
"Solid risk management should give a company a feel for the risks it is taking on board and the chance to be timely in assessing those risks," Koenig said.
"Does it prevent you from writing business that with hindsight you would have preferred not to write? Definitely not."