Big hedge funds including Marshall Wace and Odey Asset Management added to short positions against Europe's banks, regulatory filings seen by Reuters and data from Breakout Point showed.
Marshall Wace held the largest disclosed number of short positions against banks, public filings from Austria, Italy, Sweden, Britain, Spain and Poland analysed by Breakout Point showed.
The banks included BAWAG (BAWG.VI), FinecoBank (FBK.MI), Handelsbanken (SHBa.ST), CaixaBank (CABK.MC), NatWest Group (NWG.L) and PKO Bank Polski (PKO.WA).
BNP Paribas shares fell by as much as 12% on Wednesday before recovering to show a loss of 9%, while Deutsche Bank shares fell almost 9%.
In the week to Wednesday, some 120 billion euros ($126 billion) had been wiped off the value of European bank shares.