The last time Lehman Brothers' chief financial officer Erin Callan hosted a conference call with analysts, the firm's stock was in the toilet. Investors worried that it would follow the same path that Bear Stearns had taken just days before. By exuding an air of confidence and advertising total transparency, Callan gave a commentary that helped the stock rally 46 percent.

Three months later, it seems, investors aren't so easily persuaded.

This morning, Callan tried again to quell fears that Lehman is destined for failure. In a conference call announcing an unexpectedly jaw-dropping loss for the second quarter of $2.8 billion, Callan played down fears that there will be more bad news to come.

Instead, she said, the firm aggressively took action in deflating its bloated balance sheet. It effectively ripped the band-aid off swiftly so as to minimize the pain. It raised $6 billion in capital not because it needs it to compensate for losses on its tainted assets, but because it plans to use the funds to take advantage of investment opportunities in this depressed market.

While its hedges didn't really work during the quarter, Callan expects that will be only a temporary problem. While March and April weren't so kind to the markets (Bear! Peloton! Credit spreads!), May was spectacular and so was the first week of June. We've de-leveraged our balance sheet so aggressively, she said, we don't plan to reduce it further.

But Callan's confidence didn't quite have the same effect this time. While it certainly sounds like the worst is behind Lehman, as its chief executive Richard Fuld proudly proclaimed back in April, investors would have none of it. Lehman's stock remains in the toilet, down nearly 8 percent today and off by more than 50 percent year-to-date.

Was it the lawyers who took the wind out of Callan's sails? On the call, she said over and over again that the results could change materially by the time they announce their final numbers next week. That kind of disclosure is perfectly acceptable, but her emphasis on it almost had the effect of neutralizing her confidence.

How about the fact that Callan and Fuld said everything would be fine back in March and April, when Callan now says they simply didn't have the visibility that the quarter would be so horrendous? Who's to say they have any clue what the next three months have in store?

The market well knows that they don't. Lehman's $130 billion in asset sales during the second quarter are certainly commendable. Its $6 billion capital raise? A relief.

Callan said that if you were to chart Lehman's business during the quarter, it would be a straight lineup. Lehman's stock chart went straight up, too, back in March after Callan's first-quarter remarks. The problem is, it went back down.

Lehman has good reason to hope that it's out of the woods and that Fuld can finally say with total conviction the worst is behind it.

But the only certainty this market seems capable of believing is the worst one of all for Lehman: uncertainty.