Wall Street closed an uneasy session lower Wednesday as investors, uncertain if the worst of the credit crisis is over, refrained from extending Tuesday’s huge advance.

Stocks bobbed in and out of positive territory for much of the day before taking a sharp turn lower in the last half-hour. Traders may well have been rattled when the chief executive of e-Trade Financial Corp., Mitch Caplan, appeared on CNBC and talked about the online brokerage’s problems resulting from losses in its $3 billion portfolio of mortgage debt. While Caplan was upbeat, any reminder of credit-related uncertainty has easily unnerved the market – especially late in a session.

“All month long, once a direction has been established, it tends to accelerate in the last hour,” said Steven Goldman, chief market strategist with Weeden & Co., in Greenwich, Conn. “They hit a grease spot, and that was the case today, as well.”

The market was initially relieved after Bear Stearns Cos. Chief Financial Officer Sam Molinaro said the investment bank’s leveraged finance business is improving. He said the company expects to take a $1.2 billion writedown during the fourth quarter, which eased worries of even higher losses.

Wednesday’s news followed reassuring comments from Goldman Sachs Group Inc.’s chief executive about its own credit exposure that helped propel the Dow Jones industrials up nearly 320 points on Tuesday.

But more evidence of the tenuousness of the credit markets came from Britain’s HSBC Holdings PLC, which said it would have to write down a further $3.4 billion from its U.S. business during the third quarter because of exposure to subprime loans, after writing down billions earlier in the year.

Meanwhile, after plunging on Tuesday, oil prices resumed their climb Wednesday, raising concerns that inflation risks could prevent the Federal Reserve from lowering rates to calm the shaky market.

The Dow fell 76.08, or 0.57 percent, to 13,231.01. The average underwent several big revisions after trading ended, a common occurrence when there is a sharp move late in the session.

Broader stock indicators also fell. The Standard & Poor’s 500 index lost 10.47, or 0.71 percent, to 1,470.58, while the Nasdaq composite index tumbled 29.33, or 1.10 percent, to 2,644.32. [MORE]