Energy stocks slumped as the price of oil dropped to its lowest in more than four months. Oil has fallen sharply since the end of June on evidence that a global supply glut is building at the same time demand appears to be ­slowing.

The energy sector is down 15 percent this year, making it easily the worst performing industry group in the S&P 500 index. Earnings at energy companies have dropped nearly 60 percent in the second quarter.

"Certainly, oil production has been strong globally," said Serena Vinton, a portfolio manager at Franklin ­Templeton. "And with some of the global economic concerns and strong global production, it creates a nervous environment for oil."

The Standard & Poor's 500 index dropped 5.80 points, or 0.3 percent, to 2,098.04. The Dow Jones industrial average fell 91.66 points, or 0.5 percent, to 17,598.20. The Nasdaq composite slipped 12.90 points, or 0.3 percent, to 5,115.38.

Benchmark U.S. crude fell $1.95, or 4.1 percent, to close at $45.17 a barrel in New York. U.S. crude has been sliding since reaching a high this year of $61.43 a barrel on June 10.

Overall, stocks have been in the doldrums since the S&P 500 closed at an all-time high of 2,130 on May 21. Short sell-offs have been followed by short rallies as investors have weighed signs of an improving U.S. economy against signs of weakening growth overseas.

Among individual stocks, Tyson Foods was the biggest loser in the S&P 500 index. The meat producer slumped $4.39, or 9.9 percent, to $39.96 after cutting its outlook for fiscal 2015 earnings.

The company, which owns the Jimmy Dean breakfast sausage brand, blamed conditions in the beef market for its woes, citing high cattle costs and "export issues" as factors that were hurting its profits.

Apple slipped 2.4 percent to $118.44 Monday, extending its decline since February to 11 percent and dropping below another chart threshold, its 200-day moving average, for the first time since 2013.

Michael Kors was another big loser, dropping $3.28, or 7.8 percent, to $38.71 amid concern that demand for the luxury fashion retailer's handbags is dropping off. Analysts at investment bank Canaccord cut their price target on the stock ahead of the company's latest earnings report due out Thursday.

Associated Press