Updated from 10:18 a.m. EDTIndyMac Bancorp's ( IMB) precipitous fall Monday is a bad sign for other savings and loans on the brink of financial disaster. After the last session, IndyMac posted a "stakeholder letter" on the company's blog, announcing that it was no longer considered well-capitalized by its regulator, the Office of Thrift Supervision. Unless it quickly raises capital or finds a way to sell major portions of its business, IndyMac can't survive for the next several quarters unless overall housing prices show some signs of life. A rebound in housing would make the mortgage-backed securities market much more liquid, supporting prices and curtailing writedowns. It would also help to stabilize IndyMac's loan quality and enable it to pare down its quarterly provisions for loan loss reserves. Unless any of those things happen, however, IndyMac and other troubled S&Ls like Washington Mutual ( WM) and Downey Financial ( DSL) are in trouble, putting the OTS is in a very difficult position. The regulator of the nation's approximately 815 federally chartered S&Ls has already seen the second-largest institution it supervised, Countrywide, acquired under duress by Bank of America ( BAC). And WaMu and Downey are both prime candidates for actions similar to IndyMac's.