NEW YORK — Wall Street has managed an advance the hard way — zigzagging on a mix of earnings and economic news before closing moderately higher.

The major indexes changed course several times in yesterday's session, rising in response to Pfizer Inc.'s $68 billion planned acquisition of Wyeth, a deal that reassured investors that mergers could still take place in a recession. And the National Association of Realtors said existing homes rose rather than fell in December, stirring hopes that lower prices and falling interest rates are starting to erase a glut of homes with "for sale" signs.

Analysts expected that with earnings reports flooding in, the market would have a hard time sorting through all the data and settling on a direction.

They're also expecting more volatility as reports continue over the next two to three weeks.