U.S. stocks closed modestly lower on Monday as a deepening slump in crude oil prices pulled down energy and mining stocks on a lighter than usual day of trading.

Chevron fell 1.8 percent, the most in the Dow Jones industrial average. Consol Energy sank 9 percent.

After recovering a bit last week, U.S. crude oil fell 3 percent amid reports that Iran intends to increase exports by 500,000 barrels a day once economic sanctions are removed. That would only add to excess global supplies that have helped depress oil prices.

The Dow lost 23.90 points, or 0.1 percent, to 17,528.27. The Standard & Poor's 500 index declined 4.49 points, or 0.2 percent, to 2,056.50. The Nasdaq composite shed 7.51 points, or 0.2 percent, to 5,040.99.

With less than a week to go in 2015, the Dow is down 1.7 percent for the year, while the S&P 500 is essentially flat with a loss of 0.1 percent. The Nasdaq is up 6.4 percent for the year.

Energy and mining companies felt the brunt of the sell-off Monday.

Chevron fell $1.69 to $90.36, while Exxon Mobil lost 59 cents, or 0.7 percent, to $78.74. Consol Energy tumbled 78 cents to $7.87, while Chesapeake Energy slid 38 cents, or 8.5 percent, to $4.07.

Mining company Freeport-McMoRan sank 9.5 percent following news that James R. Moffett, the company's executive chairman and co-founder, is stepping down. Plunging commodity prices have led to mass layoffs across the entire industry. The move follows the recent revelation that activist investor Carl Icahn has taken a huge stake in the company. The stock shed 72 cents to $6.85.

Six of the 10 sectors in the S&P 500 index moved lower. Energy stocks fell the most, 1.8 percent. The sector is down 23.2 percent this year. Consumer discretionary stocks fared the best, gaining 0.3 percent. That sector is the best performer so far this year, up 9.1 percent.

Trading volume was lighter than usual following the Christmas holiday weekend. That's likely to be the case this week, as well, ahead of the New Year's Day holiday, said David Schiegoleit, managing director of investments at the Private Client Reserve at U.S. Bank.

Benchmark U.S. crude shed $1.29, or 3.4 percent, to close at $36.81 a barrel on the New York Mercantile Exchange.

Brent crude, which is used to price international oils, lost $1.27, or 3.4 percent, to close at $36.62 a barrel in London.

Precious and industrial metals prices ended broadly lower. Gold slipped $7.60 to $1,068.30 an ounce, silver dropped 50 cents to $13.88 an ounce and copper fell 5 cents to $2.08 a pound.

Bond prices rose. The yield on the 10-year U.S. Treasury note fell to 2.23 percent from 2.25 percent.

The dollar slipped to 120.36 yen while the euro fell to $1.0971.