Banks are scrambling to try to get out of the credit-crisis quagmire, but many investors don't believe that they can.

Financial shares fell in Europe today after the Swiss bank giant UBS announced a shake-up of its board.

In the United States, shares of Lehman Brothers fell 8 percent on Monday, to the lowest point since 2000, amid a broad sell-off of financial stocks in the United States. Lehman has been buffeted by rumors about whether it can survive as an independent investment bank, and there was a rumor on Monday that Barclays had made a discount offer of $15 per share for Lehman, which closed on Monday at $19.81.

Andrew Ross Sorkin of the New York Times dismissed that talk on CNBC this morning. And Lehman shares may get a boost from a "buy" recommendation from Morgan Stanley analysts.

"We think near-term risk of incremental write-downs is balanced by solid liquidity and capital footing," the analysts wrote.

UBS announced its changes in response to shareholder criticisms that the bank did not react quickly enough when the U.S. subprime mortgage market collapsed. Since October, UBS has written down nearly $37 billion worth of assets.

Four directors will step down this fall. The bank also outlined new corporate governance guidelines and increased the role of Sergio Marchionne, the nonexecutive vice chairman. Marchionne, the chief executive of Fiat, will also become the senior independent director on the board.

Saying that "bringing UBS back to its leading position" is his top priority, Peter Kurer, who became chairman of UBS in April, said that, "we have the foundations for the energetic and rigorous execution of our mandate."

But the moves did not impress shareholders, and they came a day after the United States Department of Justice asked a court on Monday to order UBS to turn over data on wealthy American clients suspected of evading taxes.*

Shares of UBS fell as much as 7 percent, to a 10-year low, in Zurich trading before recovering a bit. Other bank stocks slumped in Europe.

"We reiterate our cautious investment recommendation on UBS as near-term challenges are significant," said Folkert Jan Van Der Veer, an analyst with Dresdner Kleinwort, according to the Financial Times' Alphaville blog. "The threat of legal action in the U.S. could put management in a delicate and undesired position whereby it may have to hand over client information in order to avoid legal repercussions."

All the bad news surrounding UBS has clearly had an impact on employee morale. The bank's chief executive, Marcel Rohner, sent an email to UBS employees this weekend in an effort to lift their spirits, the New York Post reports. The good news? Lower-level employees will get an extra day off this year.

*Update 4:26pm: A Federal judge in Miami authorized the Internal Revenue Service to request the information from UBS.