US stocks fell on as Iran’s vow to push ahead with its nuclear program drove oil prices higher and home improvement chain Lowe’s Cos. Inc. gave a disappointing outlook.

Shares of Lowe’s, the No. 2 US home improvement chain, fell more than 4 percent, dragging down shares of top-ranked rival Home Depot Inc. and those of companies that supply home fixtures.

Lowe’s cut its sales and earnings outlook, offering yet another sign of weakness in the housing sector.

Crude oil prices rose close to $72 a barrel after Iran, the world’s fourth-largest oil exporter, said it would not suspend nuclear work as its deadline to respond formally to proposals from six major powers drew near.

“The risk for crude isn’t to the downside. It’s to the upside,” said Michael Malone, trading analyst at Cowen & Co. in New York.

Higher oil prices tend to weigh on the broader stock market because they mean increased costs for business and consumers, but they also lift shares of energy companies.

Shares of Exxon Mobil Corp., the world’s biggest publicly traded oil company and a Dow component, rose 0.7 percent to $69.57 on the New York Stock Exchange (NYSE).

Shares of defensive companies, whose products consumers can’t do without even in an economic downturn, also gained. Procter & Gamble Co., whose products include Tide detergent and Pampers disposable diapers, were up 0.7 percent at $60.81 on the NYSE.

But shares of Lowe’s dropped 4.3 percent to $28.24 on the NYSE. Shares of rival Home Depot fell 1.8 percent to $34.13, while those of American Standard Cos. Inc., whose products include kitchen and bathroom fixtures, shed 1.7 percent.

In addition, Lowe’s second-quarter profit missed Wall Street’s estimates. US crude oil for September delivery rose 56 cents to $71.70 a barrel, slightly off an earlier session high at $71.90.