Worthless securities have tax value.

If a stock you’ve held becomes worthless, as was the case with Enron and Worldcom stock some years ago (and likely will be the case with Lehman Brothers), all is not lost. You can claim a tax write-off for it. Treat the loss—what you paid for it plus any broker’s commissions and reinvested dividends—as a capital loss (short-term if you held the stock for a year or less; long-term if you held it for more than a year). Claim the loss only in the year the stock became completely worthless. If you learn now that stock you own became worthless in a prior year, you have 7 years to amend an old return to report the loss. After 7 years, you’re completely out of luck.