????Lucent Technologies
????Loss: $274 billion
????Peak market cap: $285 billion (December 1999)
????Recent market cap: $11 billion (2006 merger with Alcatel)
????Ticker: ALU

????Lucent was one of the great telecom success stories of the late 1990s. But the company was soon unmasked as little more than a hype job, using aggressive accounting to pad its earnings. The company later agreed to settle SEC fraud charges -- though not before telling Fortune the case was really just a "failure of communication." That earned Lucent a $25 million failure-to-cooperate slap on the wrist two years before it was sold to French communications firm Alcatel.

????AIG
????Loss: $239 billion
????Peak market cap: $242 billion (December 2000)
????Recent market cap: $3 billion
????Ticker: AIG

????A list of losers would hardly be complete without a mention of AIG, the cratered insurer that has taken $180 billion of federal aid. Under former CEO Hank Greenberg, the company appeared placid from the outside, even as it was taking on more leverage to juice its earnings and building up some of the risks that later led to its derivatives-fueled downfall. AIG is now working to repay taxpayers, though no one expects to see a check in the mail soon.

????America Online
????Loss: $219 billion
????Peak market cap: $222 billion (December 1999)
????Recent market cap: $3 billion
????Ticker: AOL

????Under founder Steve Case, AOL built a formidable user base and became synonymous with the consumer Internet. But Case (right) and Time Warner's Gerald Levin agreed in January 2000 to a merger that would soon be judged among the worst ever, with the combined company racking up $99 billion in losses in a single year. AOL has since freed itself from Fortune and CNNMoney.com parent Time Warner, but the once ubiquitous "you've got mail" tagline now elicits shrugs.

????Exxon Mobil
????Loss: $192 billion
????Peak market cap: $509 billion (December 2007)
????Recent market cap: $317 billion
????Ticker: XOM

????Exxon Mobil has been the most valuable U.S. company since 2006, when it passed GE, and it hasn't suffered a decline as large as the big tech companies did earlier this decade. Even so, the company's value has shrunk dramatically. Its shares have dropped along with the market and management has reduced the share count via aggressive buybacks.

????WorldCom
????Loss: $186 billion
????Peak market cap: $186 billion (April 1999)
????Recent market cap: $0 (bankruptcy filing July 2002)

????Enron didn't make this list because its peak market value of about $70 billion was too small. But the other big fraud of the early Aughts did. WorldCom -- the telecom rollup headed by former high school basketball coach Bernie Ebbers (right) -- was such a voracious acquirer and issuer of shares that it was a megacap at its peak. But shortly after it became apparent that Ebbers & Co. were cooking the books, WorldCom filed for Chapter 11 bankruptcy protection in 2002. Ebbers was convicted of fraud three years later.