UPDATED: Apple shares fell 10% Thursday — with the tech giant losing about $72 billion in market-cap value — a day after the company issued a rare earnings warning that it chalked up largely to sluggish iPhone sales in China.

Apple surprised Wall Street on Wednesday afternoon after the market closed by issuing revised guidance for its year-end 2018 quarter in a letter from CEO Tim Cook to investors. The tech behemoth had projected total revenue for the quarter to come in around $91 billion but now is forecasting about $84 billion.

The drop in Apple shares dragged down the Dow Jones Industrial Average index, which fell 660 points, or 2.8%, on Thursday. Investors fears about a global economic slowdown were also stoked by weaker-than-expected data about the U.S. manufacturing sector released Thursday.

Apple’s stock price hovered around the $143-$145 mark in the first few minutes of trading, down about 9% from Wednesday’s closing price of $157.92. It ended the day down 9.96%, to $142.19 per share. That’s the lowest price for Apple stock since July 2017 and its biggest single-day stock drop in six years.

Last summer, Apple stock was riding high: In August, it became the first U.S. company to surpass the $1 trillion market cap mark. The stock’s decline in the fall was fueled by concerns over slowing iPhone sales after Apple reported results for the September quarter, as well as a broader sell-off by tech investors. Apple’s market cap now stands at about $675 billion.

Apple’s first instance of revised earnings guidance since 2002 rattled financial markets as it put the spotlight on China’s woes and the dependence of the largest U.S. companies on strong growth in the world’s second-largest economy.

Apple’s tech peers saw modest declines in a down market but not on the same scale as the Apple sell-off. Netflix ended the day better than others, closing up 1.3%, with declines for Facebook (-2.9%), Google (-2.85%) and Amazon (-2.5%). Media conglomerates hit by the downturn included Disney (-2.4%), Viacom (-1.9%), Lionsgate (-1.6%) and 21st Century Fox (-0.65%), with gains posted by Comcast (+0.8%) and CBS (+1.0%).