Even though some big-name U.S. stocks remain far below their 1999 peaks, investors whose portfolios were well-diversified may not think of the decade as lost. The 2000s produced inflation-beating returns in many smaller-company stocks and in shares of firms in emerging economies, as well as in commodity investments such as gold.
Mutual funds that buy small-company stocks believed to be undervalued, for example, gained an average of 8.3% a year in the decade, while the Standard & Poor's 500 index's return was a negative 1.2% a year, even including dividends earned, according to fund industry data.
Emerging-market mutual funds -- increasingly popular in recent years as more Americans sought to invest in fast-growing economies abroad -- rose 9.3% a year, on average, in the 10 years.
Wharton's Siegel notes that the dismal performance of U.S. blue-chip stocks and tech issues measured from the end of 1999 reflects that those shares "began the decade at the top, in the biggest bubble in history."
The S&P 500 index, inflated by tech stocks at the time, peaked in March 2000.
One classic way to judge a stock's risk is to look at the price relative to the company's per-share earnings. In March 2000, the average S&P 500 stock's price-to-earnings ratio was an extraordinarily high 27 based on estimated 2000 operating earnings.
That ratio now, based on earnings estimates for 2010, is 15, according to S&P.
"This was the 'correction' decade from the excesses of the '90s," Siegel said.
Robert Shiller, a Yale University economics professor whose book "Irrational Exuberance" in 2000 warned that the stock market was severely overheated, said he agreed with Siegel that "the market now is more reasonably priced.
"That would seem to portend against another lost decade" for stocks, Shiller said.
Still, like many experts, he said he worries that the financial-system crisis has hurt the economy's long-term prospects in ways we may not yet fully appreciate.
In the short term, one crucial issue is whether the economy can stand on its own once the government and the Federal Reserve begin to withdraw the massive financial support they've provided.
Longer term, as millions of Americans save more and spend less to repair their finances and pay down a mountain of debt, the risk is that the economy could experience weak growth for years to come.
That scenario could translate into relatively feeble corporate earnings, undercutting stocks' appeal.
One theme popularized by Newport Beach-based bond fund giant Pimco is that the U.S. economy has entered a "new normal," which will be characterized by slow growth and intensive regulation of the financial system.
"A simple way to look at it is that private market capitalism simply went too far over the last 10 to 20 years, and now we're in the process of pulling back," says Pimco founder Bill Gross.
He believes that will mean much lower-than-normal stock market returns in the years ahead. Still, even Gross hasn't gone so far as to suggest that another lost decade looms.
An investor for 40 years, Olivares says she figures the odds favor that history won't repeat.
She still has faith, she said, that "over the long term, stocks are the way to go."