Updated from 1:14 p.m. EDTAt a time when Delta Air Lines' ( DAL) corporate leadership is needed to step up and help the troubled airline completely rethink its business model, executives are stepping out to take jobs elsewhere. As a result, Wall Street and investors are losing faith in the company, where the situation will almost certainly have to get worse before it gets better. The day after Delta announced a first-quarter loss of $384 million, three times what rival Continental ( CAL) lost in the first quarter, the company said CFO Michele Burns is leaving the company to take the same post at Mirant's ( MIR) at the end of the month. The news comes a week after the retirement of Terry Erskine, a key negotiator with the company's labor unions, and less than a month after President and COO Fred Reid left to join Virgin's soon-to-be announced low-cost airline serving the U.S. Shares were off 63 cents, or 8.2%, to $7.07, a hair shy of their 52-week low of $7 set in March. Including today's stumble, shares of Delta are off about 40% year to date. "Michele was a valued member of Delta's management team, and we wish her well," said Katie Connell, spokeswoman for Delta, adding that CEO Gerald Grinstein will be meeting with the board and "announcing a replacement soon." In reaction to the big loss and uncertainty around Delta's future, Prudential Equity Group analyst Dan Hemme downgraded the company to underweight from neutral weight, becoming the third brokerage to put a sell rating on the stock. Specifically, Hemme pointed out that the management changes have put the announcement of the company's restructuring plan off its original track, delaying it from June to late August.