Dow futures sink 600 points, adding to the market's 3-week losing streak

U.S. stock futures fell sharply early Monday as a number of factors rattled traders amid a three-week losing streak for the market.

Dow Jones Industrial Average futures lost 610 points, or 2.2%. The move indicated an opening drop of 550 points. S&P 500 futures lost 1.8%. Nasdaq 100 futures fell 1.5%.

Here's what traders were watching Monday morning:

• The U.K. is reportedly considering another national lockdown to stop an increase in coronavirus cases. The country's benchmark FTSE 100 dropped more than 3% on the fear. Here in the U.S., stocks that would be hit hardest from another lockdown decline in premarket trading. Share of Carnival Corp. were off by 5%. Southwest Airlines and Delta Air Lines both fell 4%. 
• Negotiations for a second stimulus bill could become more complicated after the passing of Supreme Court Justice Ruth Bader Ginsburg, which could lead to a bitter nomination process ahead of the election. Trump said he would nominate someone this week to take Ginsburg's seat. Republicans and Democrats have been in a stalemate since July after provisions from the previous stimulus bill expired. Chris Krueger, Washington strategist at Cowen, said in a note that a new coronavirus stimulus bill is now "unlikely until post-Nov. 3 as the fight over Justice Ginsburg's empty seat will consume D.C."
• Technology shares — which led the broader market off its coronavirus lows and into record territory, but have been hit hard so far in September — struggled once again in the premarket. Apple, Microsoft and Amazon were all off by 2% in premarket trading.
• Shares of Nikola, a one-time high-flying SPAC-turned electric vehicle play, dropped 27% in premarket trading after the company said founder Trevor Milton is voluntarily stepping down as executive chairman and board member. The move comes after a short-selling firm Hindenburg Research accused the company of fraud. The SEC and Department of Justice are reportedly investigating the company as well. Shares of GM, which recently took a 11% stake in Nikola, fell almost 4% in premarket trading.
• Bank stocks sold off across the board after a report that found a number of global banks allegedly moved illicit funds. A new investigation by BuzzFeed and the International Consortium of Investigative Journalists found the banks' internal compliance officers flagged a total of more than $2 trillion in transactions between 1999 and 2017 as possible money laundering or other criminal activity. Shares of Deutsche Bank dropped nearly 8%, while JPMorgan fell almost 5% in premarket trading.
• Meanwhile, tensions between the U.S. and China keep escalating. China's Ministry of Commerce released long-awaited provisions on its so-called "unreliable entity list," a day after the U.S. announced a ban on WeChat and TikTok.

"It seems like the biggest reason for the decline in most global stock markets is the concern that tighter virus restrictions in Europe will result from the new spike in Covid cases now that the colder weather is upon us," Matt Maley, chief market strategist at Miller Tabak, said in a note on Monday.

The S&P 500, Dow Jones Industrial Average and Nasdaq Composite all fell for a third straight week last week. That marks the market's longest weekly slide since 2019. Facebook, Amazon, Apple, Netflix, Google-parent Alphabet and Microsoft all posted steep weekly losses. The tech-heavy Nasdaq Composite is in correction territory, down more than 10% from its recent record high. It's been a rough month so far for the market and technology shares. The S&P 500 is off 5% so far in September. 

Tech is coming under pressure in part on valuation concerns within the space as well as options of individual stocks, ETFs and indexes expired.

"For the market to hold these levels buyers have to come into the technology sector over the next week to 10 days," said Marc Chaikin, CEO of Chaikin Analytics, in a post. "Without the impetus of the call option buyers who helped propel the large-cap tech stocks to extreme valuations, it is unlikely that the subsequent rally can exceed the September peak."

"The other narrative is that this avails Democrats to run the successful 2018 playbook again: GOP trying to take away healthcare," he said.

— CNBC's Yun Li contributed reporting.

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