Historically when the U.S. stock market has declined, investors have viewed it as a buying opportunity, confident that equities would climb in the long term. But they are starting to lose that faith, The Wall Street Journal reports.

The Standard & Poor’s 500 Index recently stood 25 percent below its October 2007 record high.

And investors are concerned that Europe’s debt crisis and sluggish economies around the world will push stocks down further.

NYSE traders (Getty Images photo)

The stock market’s recent extreme volatility is spooking investors too.

"People were holding out hope that we were going back to normal," after the financial crisis of 2008-09, Philip Poole, head of investment strategy at HSBC Asset Management, tells the Journal.

"We're not going back to normal. The post-crisis world will be different . . . but that message takes a long time to hammer home."

Many statistics illustrate the pessimism permeating stocks.

Investors withdrew $92 billion from developed countries’ stock markets in the three months through August, according to research firm EPFR. That move continued in the first three weeks of September, with another $25 billion of withdrawals.

While the stock market has rebounded Monday and Tuesday amid optimism that Europe is getting its act together, the negative drumbeat of news may resume soon.

"The way things are going, we're going to be in a recession by the end of the fourth quarter," Barton Biggs, of money manager Traxis Partners, tells Reuters.