Apple Plunges $57 Billion in Premarket Trading, Dragging Global Stocks After Shock Sales WarningGlobal stocks slid after a shock revenue-guidance downgrade from Apple and troubling comments about the economic impact of the U.S.-China trade war from CEO Tim Cook.

After a roller-coaster day of trading to start 2019, global markets were enduring more turbulence Thursday after Apple warned investors that sales were slowing in China, reigniting fears about a slowdown in the world's second-largest economy.

"While we anticipated some challenges in key emerging markets, we did not foresee the magnitude of the economic deceleration, particularly in Greater China," Apple said after the close of trading on Wednesday.

Apple plunged 8% in after-hours trading and was down 7.7% in US premarket trading as of 1:10 p.m. in London (8:10 a.m. in New York). The rest of the so-called FAANG stocks (Facebook, Amazon, Netflix, and Google) followed Apple lower, and the slump in tech shares dragged down global markets.

Apple'sshock revenue-guidance downgrade, along with troubling comments from CEO Tim Cook about theeconomic impact of the US-China trade war, added to fears that had already gripped investors.

“和美国之间的贸易紧张关系China put additional pressure on their economy," Cook said in an interview with CNBC on Wednesday.

Cook's words, as well as continuing fears around monetary-policy tightening from global central banks and a general slowdown in the world economy, have helped push markets downward on the second day of trading in 2019.

Here's the scoreboard:

• FAANG stocks slid,with Facebook down 1%, Amazon down 1.1%, Netflix down 1.4%, and Google down 1.6% in premarket trading.
• U.S. stocks looked set for a substantial dropThursday following Cook's comments, which came after markets closed on Wednesday. Futures pointed to a fall of 1.8% in the tech-heavyNasdaq, while both theS&P 500and theDow Jones Industrial Averagewere set to open 1.1% lower.
• In Asia, China'sShenzhen Compositeended 0.8% lower, while Japan'sNikkei 225lost 0.3%.
• As European trading kicked off, shares also fell, with theEuro Stoxx 50broad index down 0.65% andGermany's DAXdown 0.9%.

Thursday's market moves extend a brutal start to the new year after 2018 ended on a sour note for markets. The S&P 500 fell 6.2% in 2018, booking its worst year since the financial crisis and worst December since the Great Depression.