"Even as it approaches, Sandy has provoked some disruption to the economy via precautionary measures" taken to protect the population, noted analysts at the Zurich Cantonal Bank (ZKB).
In New York, one of the world's leading stock markets will be closed on Monday and possibly on Tuesday as well, market operator NYSE Euronext has said, the first time trading has been cancelled since the September 11th 2001 terror attacks.
"If Sandy hits major cities, we should expect serious damage, not only material damage but also through disruptions to business activity," ZKB analysts said.
They forecast that the world's second-biggest reinsurance company, Swiss Re, could face claims totalling several billion dollars, possibly even more than those incurred from Hurricane Katrina in 2005.
That storm resulted in a total $72 billion in damage covered by commercial insurance companies, of which Swiss Re had covered $1.2 in turn.
Analysts at the Swiss asset manager Vontobel estimate that damage from Hurricane Sandy would probably not exceed the quarterly budget of major insurers however, and add that Swiss Re should be able to pay a dividend this year.
Shares in Swiss Re fell by three percent to 62.95 francs in midday trading while those in Zurich Insurance Group were off by 2.88 percent at 226 francs.
The SMI index of leading Swiss shares have given up a slight 0.08 percent overall.