It's the basic question when investing in a stock: is it on the way up or will it go down? To answer this question,  Wall Street has developed numerous ways of attempting to predict what will happen, estimating various attributes tied to stock performance in order to determine what the future holds for a company's valuation. After dissecting the data, analysts following a particular stock produce a price target of where they believe the  stock is headed. Out of the entire S&P 500, which stocks are analysts expecting to have the biggest price drops?  Here's the top 20, according to ThomsonReuters (as of market close on 10/16/09). Click ahead to find out!

A late rally pushed stocks higher Tuesday following better-than-expected earnings from several Dow components. The Dow logged its seventh-straight gain, the Nasdaq, it's tenth.

The Dow advanced Tuesday as a slew of components beat earnings expectations. But there were pockets of weakness throughout the market, including chips, hardware, banks and retail. The Nasdaq was lower.

The Dow bolted out of the gate Tuesday as a slew of components beat earnings expectations. But there were pockets of weakness throughout the market, including chips, hardware, banks and retail. The Nasdaq was lower.

Futures indicated a slightly lower open for Wall Street Tuesday ahead of a slew of earnings and Federal Reserve Chairman Ben Bernanke's Capitol Hill testimony.