Shares of several major U.S. investment banks fell in high volume before the opening bell on Thursday as concern about credit availability worsened.

Shares of Lehman Brothers Holdings Inc. were down 1.8 percent to $50.60, Bear Stearns Companies shares were down 1.6 percent to $101.51 and Goldman Sachs Group Inc. fell 1.2 percent to $162.85.

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