Take a look at some of the biggest movers in the premarket.

Didi — Shares of Didi sunk about 20% in premarket trading after Chinese regulators announced a cybersecurity review of the ride hailing company late Friday. The move came less than a week after Didi’s public debut on the New York Stock Exchange.

Full Truck Alliance and Boss Zhipin — Chinese regulators also launched an investigation into Boss Zhipin and subsidiaries of Full Truck Alliance, which are both listed in the U.S. Shares of Boss Zhipin, listed under the name “Kanzhun,” fell roughly 10% in early trading. Full Truck Alliance shares plunged about 16% in the premarket.

Other Chinese companies — Shares of other Chinese companies publicly traded in the U.S. also dropped after regulators announced cybersecurity reviews. Baidu, Pinduoduo and JD.com shares fell roughly 2% in premarket trading.

Oil stocks — Oil company shares rose as oil prices rose to 6-year highs after talks between OPEC and oil-producing allies were postponed indefinitely. The S&P Oil and Gas ETF gained 1.8% in the premarket, while shares of Occidental Petroleum added 1.9%, ConocoPhillips shares increased 1.7% and APA Corporation‘s stock ticked 2.2% higher.

American Express — American Express shares gained 2.5% premarket after Goldman Sachs upgraded the stock to buy from neutral. The firm also set a price target of $225 per share for American Express, more than 33% above where the stock closed on Friday. Goldman Sachs said the card stock should gain from an increase in consumer spending as the economy recovers.

3M —Shares of 3M fell slightly in early trading after Credit Suisse downgraded the industrial products stock to neutral from outperform, citing challenges with legal issues. “Despite fundamental potential upside from a cyclical upturn in global IP, and potential inventory restocking, we think it will be difficult for 3M to regain its premium multiple at this point in the cycle with two, still difficult to quantify liabilities,” analyst John Walsh said.

Pfizer — Shares of the pharmaceutical company fell roughly 1% after Israel’s health ministry reported a decrease in effectiveness in Pfizer’s Covid-19 vaccine in preventing infection and symptomatic disease. However, Israel said Pfizer’s Covid vaccine remained highly effective at preventing serious illness. The announcement comes as the highly infectious delta variant spreads in Israel and around the world.