Exxon Mobil ended down 1.6%, adding to losses strucklast week after it reported second quarter earnings halved. Chevron shares lost 3.3%, also extending last week's losses by 2.2%.
The Dow Jones fell 0.5% to 17,598 points.
The S&P 500 was down 0.3% to 2,098 points, while the tech-heavy Nasdaq also shed 0.3% to 5,115.
Oil fell to the lowest level since March as traders worried about signs of weak demand and increasing supplies.
Brentslid 4.7% to $49.74 a barrel and US crude fell 3.8% to $45.34 a barrel.
"The slowdown in China feeding into a slowdown in Asia, and the question becomes how much of that is feeding into the US?" said Quincy Krosby of Prudential Financial in Newark, New Jersey.
However, she added: "We've started to see more positive data out of Europe despite the Greek situation."
Semiconductor maker AMD was the big riser on Monday, jumping 13.5% to $2.19.