Why do stocks keep falling? When will they recover?

— -- It's a question gnawing at even the most fearless long-term investors: Why won't stocks stop going down?

After the worst week for the Dow in its 112-year history, and with 401(k) balances sinking under the weight of a frozen credit market, the thought process of the rational investor is under siege. "It is hard to tell where reason ends and panic begins," says Meir Statman, a Santa Clara University finance professor who specializes in the psychology of investing.

The sheer size of the losses, the immensity of the economic uncertainty, and the global scope of the crisis has investors wondering why the world of money has become so unfriendly so quickly.

Investors are worried. They're anxious. Their heads are spinning from too many unanswered questions related to their financial security. Why is this happening? Why can't the government fix things? Why can't stocks mount a rebound — even for a day? Why is it that the Dow can drop almost 700 points in a matter of minutes?

USA TODAY talked to experts to find out.

The emotional tumult follows last week's historic fall on Wall Street, which left the broad market 42.5% off its Oct. 9, 2007, all-time high.

In just five trading days, the Dow Jones industrial average plunged 1,874 points, which adds up to an 18.2% decline. Both the point and percentage drop were weekly records.

Investors were taken on a scary ride. On Friday, the Dow plunged almost 700 points in the first few minutes of trading, only to rally more than 1,000 points to climb 322 points into the black, before falling again and closing down 128 points at 8451. It was the first-ever 1,000-plus high/low point swing in history, says Dow Jones Indexes.

Why do stocks keep dropping?

The answer: Lots of people are selling.

There are professional investors who have to sell to meet shareholder redemptions. Individuals are getting out because they're scared and want to avoid steeper losses in their retirement accounts. Some are getting out because they've lost confidence and think the global economic outlook is bleak.

"Massive liquidations by large investors keep pressuring the market in a steady stream of selling pressure," says Chuck Stutenroth of ZAR Fund Group. "Mutual funds are liquidating. Hedge funds are liquidating. Retail investors are liquidating. No one (is) waiting (around) for a bounce."