The Dow Jones Industrial Average rose 71.60 points (0.58 percent) to finish at 12,350.61.

The broad-based S&P 500 index advanced 8.82 points (0.67 percent) to 1,328.26, while the tech-heavy Nasdaq Composite gained 19.90 points (0.72 percent) at 2,776.79.

The market welcomed payrolls firm ADP's report that US companies added 201,000 jobs in March.

The private-sector hiring numbers stoked hopes for the government's keenly awaited March jobs data due Friday.

With a third month of jobs creation above 200,000, ADP said the data "removes any remaining doubt that private nonfarm payroll employment accelerated heading into 2011."

"US sentiment ahead of Friday's Labour Report improved on the heels of ADP's private sector payroll report, which showed growth of over 200,000 jobs," Charles Schwab analysts said in a client note.

Action on the mergers and acquisitions front also stimulated buying interest.

Canadian firm Valeant Pharmaceuticals made unsolicited $5.7 billion cash bid for biotech firm Cephalon, sending the latter's shares soaring 28.41 percent to $75.44, above the hostile bid of $73 per share. Valeant added 12.82 percent at $50.08.

Dow component AT&T surged 2.20 percent to $30.71 after its boss, Randall Stephenson, defended the telecom's $39 billion takeover bid for rival T-Mobile USA, a unit of Germany's Deutsche Telekom.

Two new listings had sharply different results on the first day of trading.

Shares in private-equity group Apollo Global Management fell 4.21 percent to $18.20, while Chinese Internet group Qihoo leaped 134.48 percent to $34.00.

The bond market rose. The yield on the 10-year Treasury fell to 3.45 from 3.49 percent late Tuesday, while that for the 30-year slipped to 4.52 percent from 4.55 percent.

Bond prices and yields move in opposite directions.