Stocks closed lower on Wall Street, putting major indexes deeper in the red for the week.

The S&P 500 fell 1.1% on Thursday. The benchmark index is down for the week following the biggest pullback for the market in more than two years on Tuesday.

Railroad operators were mostly higher after a tentative labor agreement was reached, averting a strike across the country that could have been devastating to the economy.

Software maker Adobe fell sharply after announcing a $20 billion acquisition of a design company and issuing a disappointing revenue forecast for the current quarter.