Shares in French bank Societe Generale fell 6 percent on Friday, dragging markets down, with traders citing concerns over the bank's derivatives operations.
Bank shares across the continent were in the red and the main stock market indexes turned negative, after starting the day on a note of optimism expecting a high non-farm payrolls number from the US.
A Societe Generale spokeswoman said she would not comment on market rumors.
Several traders said the rumor might be spurious.
European shares turned negative, with the heavyweight banking sector moving lower.
BBVA and Credit Agricole fell 5 and 3.8 percent respectively.
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