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News Summary: Stocks fall for a fourth day

The Associated Press

MIXED MESSAGES: Investors grappled with mixed messages about the economy on Tuesday. One report said that home prices in July rose the most in more than seven years. Another showed that Americans' confidence in the economy slipped in September.

POLITICAL WRANGLING: Investors are also remaining cautious as political gridlock in Washington threatens to cause a government shutdown. That could harm consumer confidence and crimp spending.

FACEBOOK FRIEND: The social network site Facebook found another friend. The stock rose $1.26, or 2.7 percent, to $48.45 after the Citigroup upgraded the company's stock to a "buy" recommendation from "neutral," because of the increasing advertising revenue contributions from its mobile website.