U.S. stock futures were about flat in overnight trading on Monday following a major sell-off on Wall Street that resulted in the S&P 500’s worst day since May.

Dow Jones futures lost 12 points. S&P 500 futures shed less than 0.1% and Nasdaq 100 futures were about flat.

The major averages tumbled on Monday A confluence of worries including an imminent Federal Reserve meeting and the lingering delta variant as well as potential economic disruptions in China.

However, stock prices closed off of their day’s lows.

The S&P 500 slid 1.7% for its worst day since May 12 of this year. The 500-stock index fell 5% from its peak intraday, reaching 1.7% at the low. The record is 4.1% away.

Its biggest single-day fall since July 19th was 614 points (or 1.8%). As the Nasdaq Composite fell 2.2%, growth areas of the market suffered the most.

Two-day Federal Reserve policy meeting begins Tuesday. Investors want to know more about Chairman Jerome Powell’s plans and how they will reduce their bond buying. Powell said last month that he sees the Fed slowing its $120 billion in monthly purchases at some point this year.

Tuesday, February 2, 2012, at 2 pm, the Fed publishes its quarterly economic forecasts. The so-called “dot plot” is a graphic that shows the Fed’s current outlooks. It also releases the statement about interest rates. ET Wednesday. Powell will have a a press conference after.

““We’ll have to prove that the Fed’s dot plots aren’t coming out in a manner that spooks market,” stated Yung-Yu Ma (chief investment strategist, BMO Wealth Management).

The weakness of China’s equity market sent shockwaves through U.S. stock markets on Monday. The benchmark Hang Seng index plunged 4% with as struggling real estate developer China Evergrande Group teeters on the brink of default.

Ma said, “We need to see evidence that the Chinese government has taken steps to address this.”

As the winter months draw near, the Delta variant continues to pose a threat to global health. Some Americans are still hesitant about vaccinating.

The stock market that is linked to global economic growth experienced losses Monday. Energy names also suffered from a drop of 2% in U.S. crude oil prices. As bond yields dropped, bank stops fell.

The Cboe Volatility index, Wall Street’s fear gauge, jumped above the 26 level on Monday, the highest since May.

The deadline for raising the debt limit and tax hikes is also a concern. Congress returned to Washington after a recess to rush to pass funding bills in order to prevent a shutdown.

September is a historically volatile month for stocks and after the S&P 500’s 16% rally year-to-date, many investors have said the market is due for a pullback. Some strategists called Monday’s sell-off a buying opportunity.

“The market sell-off that escalated overnight we believe is primarily driven by technical selling flows ([commodity trading advisors] and option hedgers) in an environment of poor liquidity, and overreaction of discretionary traders to perceived risks,” Marko Kolanovic, JPMorgan chief global market strategist, said in a note Monday.

Some others stated that volatility would continue to exist until the risk is addressed.

Ma said, “We’re certainly not convinced that the small pullback will be a buying opportunity.” There could be even more volatility, depending on how the Fed meets…similar to the debt ceiling. The overhang, then the negotiations will ensure that this fight is pushed to its limit.

Also, cryptocurrencies pulled back Monday. Bitcoin ended the day around 7 percent lower. The slide resurfaced the debate about whether bitcoin can or should serve as a safe-haven asset.

FedEx, Adobe, AutoZone and Stich Fix report quarterly earnings on Tuesday.

— with reporting from CNBC’s Hannah Miao.