Investors were in a selling mood at the end of a mostly subdued week of trading, sending U.S. stocks lower for the third day in a row Thursday.
Energy stocks led the broad decline, which gathered momentum in the final hour of trading ahead of the long Easter holiday weekend. The slide marked the lowest close for the stock market since Feb. 13 and came on a day when several major banks reported their latest quarterly results, kicking off the company earnings season.
Traders also weighed the potential for rising geopolitical tensions following news the U.S. attacked an Islamic State tunnel complex in eastern Afghanistan with the largest non-nuclear weapon ever used in combat by the U.S. military.
Bond yields continued to drop. Gold surged to its highest level since early November. The weakened versus the yen and euro.
The Standard & Poor's 500 index slid 15.98 points, or 0.7 percent, to 2,328.95. The Dow Jones industrial average fell 138.61 points, or 0.7 percent, to 20,453.25. The Nasdaq composite index lost 31.01 points, or 0.5 percent, to 5,805.15.
Small-company stocks fell more than the rest of the market. The Russell 2000 index lost 13.96 points, or 1 percent, to 1,345.24. More stocks fell than rose on the New York Stock Exchange.
The decline deepened the market's losses for the month.
Bond prices edged higher. The yield on the benchmark U.S. 10-year note fell to 2.23 percent from 2.24 percent late Wednesday.
U.S. markets will be closed Friday for the Good Friday holiday.