U.S. stock futures fell sharply on Sunday evening, with contracts tied to the S&P 500 falling more than 5% during the opening minutes of trade as an ugly stretch for stocks looked set to worsen.

S&P 500 futures (ES00) were already down 4.7% minutes after futures opened for trading on Sunday. Futures tied to the Nasdaq-100 were sitting on an even bigger loss, down 5.7%. Futures on the Dow Jones Industrial Average were off by 1,650 points, or 4.3%.

Nearly 20 minutes into the session, futures had pared their initial opening losses, but only slightly: Dow futures were down just 1,500 points, while S&P 500 futures were off by 4.2%.

After holding relatively steady earlier in the weekend and late last week, cryptocurrencies like bitcoin started to stumble Sunday afternoon. Bitcoin (BTCUSD) was down 5.6% at $78,603 on Sunday evening.

One chief investment officer blamed the carnage Sunday night on the lack of reassurance from the administration over the weekend. President Donald Trump was playing in a golf tournament in Florida on Saturday and Sunday. The latest reports from the White House press pool suggested he was on his way back to Washington.

"Last week's brutal selling pressure is set to continue on Monday, as the market is telling us that investors still lack clarity on the implications of tariffs, tariff retaliation and are worried that economic growth is likely to slow to a complete stall or recession," said James Demmert, chief investment officer at Main Street Research, in comments shared with MarketWatch via email.

The latest wave of selling comes on the heels of a punishing stretch with few precedents. The market ended last week with an historic two-day plunge after Trump shocked investors and world leaders by unveiling sweeping tariffs against U.S. trading partners. Investors are preparing for almost anything to happen in the week ahead.

"We won't mince words: Stocks crashed the last two days," said veteran technical analyst Mark Arbeter, president of Arbeter Investments, on Sunday afternoon.

The S&P 500 SPX fell by a total of 10.53% on Thursday and Friday. The Dow Jones Industrial Average DJIA fell into correction territory, while the tech-heavy Nasdaq Composite COMP joined the small-cap Russell 2000 RUT in a bear market. It was the worst two-day performance for all four major indexes since March 12, 2020.

"Remaking 80 years of Economic, Geopolitical and Domestic Governmental order, post WWII bedrocks - in 80 days - is messy business," said Julian Emanuel, head of equity, derivative and quantitative strategy at Evercore ISI, in a note. "Doing it with the 'sledgehammer' of a larger tariff than 1930s Smoot-Hawley, was bound to cause turmoil."

The prolonged uncertainty around the tariffs and an escalating global trade war has boosted asset volatility, damaged investor confidence and raised the probability that a deterioration in so-called soft, or survey-based, data "infects" hard economic data, causing stagflation or outright recession, he said.

Meanwhile, Trump's top economic advisers brushed off recession fears Sunday and said dozens of countries are looking to negotiate for better deals.

Some investors saw uncomfortable echoes of the setup heading into Black Monday, the Oct. 19, 1987, stock-market crash. Analysts at Bespoke Investment Group noted that since stocks began trading on a five-day week in 1952, there have only been three occasions when the S&P 500 has suffered a two-day decline of more than 10%: October 1987,November 2008 and March 2020.

They observed that since the introduction of the SPDR S&P 500 ETF Trust SPY, it has suffered 20 two-day drops of more than 7%. They noted that historically, SPY has tended to see a big bounce-back on the day after the prior two-day 7%+ drops, with an average gap up of 1.4% at the open followed by an open-to-close gain of another 3.06%. The full next-day average change has been +4.54% with positive returns 16 of 19 times.

The largest next-day drop following a two-day drop of at least 7% was the 2.52% fall on Oct. 8, 2008, during the depths of the 2007-'09 financial crisis, they found.

Such selloffs can leave the market substantially oversold from a technical standpoint.

"Bullishly, things look so bad it might be good," Arbeter said, noting Friday saw 90% of the stocks in the S&P 500 fall, "a sign of panic" alongside other technical indicators.

Chart support for the S&P 500, which finished Friday at 5,074.08, stands at 4,967, Arbeter said, while the top of a cup formation traced out in 2022-'23 stands at 4,800 and marks a 50% retracement of the rally off the 2022 low, which also marks the "rising and very reliable" 200-week moving average.

It's noteworthy that so far investors have seen no signs of concern about the market selloff from the Trump administration or the Federal Reserve, said analysts at Matrix Trade, in a Sunday note.

It was likely Trump wanted to maintain this hard stance over the weekend to try to make some deals, but he's unlikely to keep it up too much longer if the market plunges again on Monday, they wrote.

"Several countries could remove tariffs in the coming days which would allow Trump to claim victory and say some soothing words to the markets. However, China and the E.U. are the most important trading partners, and markets are likely to stay on edge until deals are made with them," they wrote. "At the moment, escalation looks more likely than resolution and that supports a continued decline."