Billionaire activist investor Carl Icahn said Thursday he had sold his entire stake in Apple Inc., citing the risk of China's influence on the stock.

Icahn, in an interview with cable television network CNBC, also said he was "still very cautious" on the U.S. stock market and that there would be a "day of reckoning" unless there was some sort of fiscal stimulus.

"We no longer have a position in Apple," Icahn told CNBC's "Power Lunch," noting Apple is a "great company" and CEO Tim Cook is "doing a great job."

Icahn has been a huge fan of Apple, repeatedly calling the investment a "no brainer."

He said he made roughly $2 billion on Apple, a stock he continued to tout as "cheap" despite his reservations.

But Icahn, who owned 45.8 million Apple shares, or a little less than one percent, at the end of last year, said China's slowdown influenced his decision to exit his position entirely.

"You worry a little bit — and maybe more than a little — about China's attitude," Icahn said, later adding that China's government could "come in and make it very difficult for Apple to sell there... you can do pretty much what you want there," he said.

He added, though, that if China "was basically steadied," he would buy back into Apple.

Apple shares came under selling pressure during Icahn's television interview, down $2.99, or more than 3 percent, at $94.83 late trading.

Apple on Tuesday posted its first decline in iPhone sales as well as its first revenue drop in 13 years. The company's sales dropped by more than a quarter in China, its most important market after the United States, and it forecast another disappointing quarter for global revenues.

Apple shares have fallen more than 9 percent this week.

Apple on Tuesday posted quarterly earnings of $1.90 per share on $50.56 billion in revenue, both of which missed Wall Street's expectations.

Apple's sales declined 13 percent from the prior-year period, its first year-over-year revenue drop since 2003. Sales of its key iPhone slid to 51.2 million from 61.2 million in the previous year.