NEW YORK — Signs of progress in negotiations over Greece’s debts helped launch a stock market rally Wednesday, snapping a weeklong slump.

The rally was broad: All 30 stocks in the Dow Jones industrial average and all 10 industry groups in the S&P 500 index made gains.

“Everybody’s screen is full of green,” said Matt Kaufler, a fund manager at Federated Investors.

Major indexes started higher at the opening of trading, putting the market on track for solid gains. Around midday, Bloomberg reported that German Chancellor Angela Merkel may be willing to release more money from Greece’s bailout fund if the Greek government commits to at least one move to tighten its budget. Without a deal by the end of the month, Greece faces the prospect of going bankrupt and dropping the euro.

The stock market surged after the news broke and held most of its gains until the closing bell.

The Standard & Poor’s 500 index climbed 25.05 points, or 1.2 percent, to close at 2,105.20. It was the best day for the broad-market benchmark in a month.

The Dow Jones industrial average rallied 236.36 points, or 1.3 percent, to 18,000.40, while the Nasdaq composite gained 62.82 points, or 1.3 percent, to 5,076.69.