US stock index futures fell on Monday as a slump in oil prices pounded energy stocks, with investors also bracing for another batch of dour first-quarter earnings reports and economic data.

Exxon Mobil Corp shed 2.4 percent in premarket trading and Chevron Corp 3.6 percent as US crude prices fell to levels last seen in 1999 on concerns of oversupply.

Wall Street's main indexes have rallied this month, with the S&P 500 .SPX ending Friday with its biggest two-week percentage gain since 1974 on a raft of global stimulus and hopes the virus was nearing a peak in the United States.

The Nasdaq .IXIC also registered its best two weeks since 2001, powered by new record highs for Netflix Inc and Amazon.com Inc - deemed "stay-at-home" stocks as widespread lockdowns fueled demand for online streaming and home delivery of groceries.

Still, the benchmark S&P 500 is about 15 percent below its all-time high and analysts have warned of a deep economic slump from the halt in business activity and millions of layoffs.

“There’s an early street consensus this morning that risk has run too far, too quick,” said Stephen Innes, chief global markets strategist at AxiCorp.

“With several ‘stay-at-home’ names trading at or near year-to-date highs, the risk for a round of profit-taking might be on the cards ahead of S&P 500 earnings reports this week.”

Oilfield services provider Halliburton Co slid 7.1 percent after joining bigger rival Schlumberger  in taking impairment hits in the first quarter and issuing a bleak outlook for its North American business.

Oil-related firms Apache Corp, Marathon Petroleum, Hess Corp and Schlumberger fell between 5.2 percent and 14 percent.

After US banks kicked off the quarterly earnings season with painful forecasts for 2020, investors will keep a close watch on reports from Delta Air Lines Inc, Southwest Airlines Co and Netflix Inc later in the week.

At 7:44 am ET, Dow e-minis 1YMcv1 were down 462 points, or 1.91 percent, S&P 500 e-minis EScv1 were down 52 points, or 1.81 percent and Nasdaq 100 e-minis NQcv1 were down 87.5 points, or 0.99 percent.

Hopes have also risen for a gradual reopening of the economy after President Donald Trump cited signs of plateauing in the virus outbreak last week and outlined new guidelines for states to pull out of shutdowns.

But his plan was thin on details and left the decision largely up to state governors.

“The recovery will be much slower than the market is currently pricing in simply because social distancing measures can be relaxed but not removed until we have a vaccine or a very effective cure,” said Andrea Cicione, head of strategy at TS Lombard in London.

In economic news, surveys on April US manufacturing and services sectors are due on Thursday, while US jobless claims are forecast to have hit as many as 5 million in the week ended April 18, on top of 22 million claims in the previous four weeks.