For hedge fund billionaire Bill Ackman, the subprime mess could have a very silver lining. After Ackman started his charitable Pershing Square Foundation last year, he announced that he would seed it with the profits from two big bets: his purchase in July of 9.6 percent of Target's stock, and his long-standing wager on the failure of bond insurers MBIA and Ambac. That deal could make his foundation very wealthy: If MBIA continues dropping (and barring an unlikely government bailout), Ackman's Pershing Square Capital Management fund could gain billions. In late November (see below left), ­ Ackman pledged to the foundation the $500 million profit he's personally anticipating from his gamble.

Target's looking a bit rockier. Ackman had promised a third of any Target profits to the foundation, but since the fund bought in (see below right), the stock has fallen 24 percent.

Ackman says he'll make good on his pledge, whether he uses his winning chips or his wallet. "I'm going to give away the vast majority of whatever I make going forward," he says. He's already given the foundation $40 million and has donated several million-dollar parcels to charity.