Wall Street rallied on Monday, with the S&P set to reverse a three-day sell-off, as a weak U.S. dollar and better-than-expected home sales data encouraged investors.

The National Association of Realtors said sales of previously owned U.S. homes rose at a faster-than-expected pace to the highest in more than 2-1/2 years. The Dow Jones U.S. Home Construction index <.DJUSHB> gained 0.7 percent.

The rise in home sales was primarily driven by the credit for first-time home buyers. But still, given the unemployment rate and given the number of foreclosures, you have to be very pleased about the numbers. It's stellar, said Tim Speiss, leader of Personal Wealth Advisors group at Eisner LLP in New York.

The Dow Jones industrial average <.DJI> was up 145.03 points, or 1.41 percent, at 10,463.19. The Standard & Poor's 500 Index <.SPX> was up 17.62 points, or 1.61 percent, at 1,109.00. The Nasdaq Composite Index <.IXIC> was up 33.53 points, or 1.56 percent, at 2,179.57.

The U.S. dollar index <.DXY> slid 0.7 percent on comments by St. Louis Federal Reserve President James Bullard that the Fed should extend its mortgage-related assets purchase program to give policy-makers more flexibility.

Energy shares got a boost as January crude futures gained 2.3 percent to $79.22. Dow component Chevron Corp was up 2.9 percent at $79.

On the Nasdaq, News Corp rose 1.6 percent at $12.17 after sources said Microsoft Corp has talked about a deal in which News would get paid to take its news websites off Google Inc .

Microsoft added 1 percent at $29.93, and Google increased 2.4 percent at $583.65.

On the downside, Ciena Corp shed 8.4 percent to $12.07 after it agreed to buy the optical networking and ethernet equipment businesses of bankrupt Nortel Network .

The Morgan Stanley Healthcare Payor index <.HMO> gained 4.1 percent, while the AMEX Pharmaceutical index <.DRG> was up 1.2 percent, buoyed by news that U.S. President Barack Obama's healthcare reform plan cleared an important Senate hurdle over the weekend. But lawmakers warned of challenges ahead in winning support for passage, even among Obama's fellow Democrats.

(Reporting by Angela Moon; Editing by Jan Paschal)