Greek lawmakers passed a cost-cutting bill that had to be approved before international lenders would release $17 billion in rescue funds.
An unexpected pickup in manufacturing in the Midwest also helped push stock indexes higher.
The Dow Jones industrial average is up 153 points, or 1.2 percent, to close at 12,414 Thursday.
The S&P 500 is up 13, or 1 percent, to 1,321. The Nasdaq composite is up 33, or 1.2 percent, to 2,774.
Three stocks rose for every one that fell on the New York Stock Exchange. Volume was average at 3.8 billion shares.