NEW YORK — U.S. stocks plunged Thursday as losses for Cisco Systems hurt technology companies while Wal-Mart declined after its latest quarterly report. Banks also dropped as bond yields and interest rates sank for a second day.

It was the second-worst day for stocks this year, which has seen few large declines. Along with technology companies and retailers, transportation companies skidded and all of the industrial, financial and basic materials companies in the S&P 500 fell. Those sectors tend to struggle when investors are concerned about economic growth, although there weren’t any specific signs of economic trouble Thursday.

The Standard & Poor’s 500 index dropped 38.10 points, or 1.5 percent, to 2,430.01, its lowest close since July 11. The Dow Jones industrial average tumbled 274.14 points, or 1.2 percent, to 21,750.73. The Nasdaq composite sank 123.19 points, or 1.9 percent, to 6,221.91. The Russell 2000 index of smaller-company stocks fell 24.59 points, or 1.8 percent, to 1,358.94.

High-dividend stocks like utilities and real estate companies fared slightly better than the rest of the market, although they still finished lower. About 95 percent of the companies in the S&P 500 finished with losses.