The 10 largest prime money funds raised their euro zone bank exposure by 24 percent from September, bringing their holdings to 13 percent of total assets.

This was the fourth monthly increase in euro zone exposure among these funds, whose combined assets were $654 billion, or 46 percent of the $1.42 trillion assets held by all U.S. prime funds.

The funds' exposure to French banks rose to 5 percent of assets, up from 3.9 percent and the highest level since October 2011, when it was 5.5 percent.

Half of that exposure in French banks was in certificates of deposit, commercial paper, repurchase agreements and other short-term debt issued by Societe Generale, according to the rating agency.

Moreover, the funds' exposure in German and Dutch banks rose by 25 percent and 19 percent, respectively, in October.

Still, the euro zone exposure of these funds, which are major investors in short-term bank debt, remained about 63 percent below the end of May 2011, when the euro zone debt crisis flared up again. Their French bank paper holdings in October were more than 70 percent below their May 2011 levels, Fitch said.

Meanwhile, the biggest prime funds reduced their holdings in perceived safer Swiss, British, Japanese and Canadian banks. They also scaled back holdings of U.S. Treasuries last month.

(Reporting by Richard Leong. Editing by Andre Grenon)

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