Icahn: 'Quite concerned that something is going to happen' with stock market

Icahn: High yield market in bubble
Icahn: High yield market in bubble
Icahn: Apple a 'no brainer'
Icahn: Apple a 'no brainer'
Icahn: Real problem with eBay
Icahn: Real problem with eBay

The high-yield market is in a bubble, according to Carl Icahn.

Speaking with CNBC's "Fast Money," the activist investor revealed his thoughts on high-yield bonds, and the stock market. Icahn, who heads Icahn Enterprises, admitted he is worried about a major event—especially given the Federal Reserve's policy.

"The Fed has made it clear that they're not going to raise interest rates so fast—this market follows the Fed," he said, adding "I am quite concerned that something is going to happen."

Carl Icahn
David Grogan | CNBC

Icahn also said the index would be "meaningfully lower" without the actions of the Fed.

As for bonds, Icahn revealed he is betting that the high-yield market is due for a fall.

"I think the high-yield market is in a bubble," he said. "I think that is a no-brainer."

Read More Marc Andreessen: Icahn's like 'evil Captain Kirk'

Icahn also touted some of his stock calls, including his big bet on Apple.

Although he said he does not remember if he has bought any more Apple stock recently, Icahn reiterated his belief that "companies like this come around once a decade." Not only does he expect the stock to go up as Apple continues to perform well, he said, but there may also be a big boost from traders forced to cover their shorts against the tech giant.

The activist investor also discussed eBay, and its decision to spin off its PayPal division.

Read More What the eBay Split Means for PayPal

"They're a great company—PayPal is great—but it could disappear quickly if something isn't done quickly," he said. "I'd like them to explore selling it right now."

Even the online payment system's current dominance could disappear, Icahn said.

"PayPal is a jewel right now because it really controls all the small merchants online, and they like them, and they get along—PayPal is almost necessary," he said. "But that's not going to last forever. Not with Apple Pay there, and I'm sure the Android is going to get into it."