Carl Icahn: I should have bought more during initial postelection dip

Billionaire activist investor Carl Icahn said that while the market has gotten ahead of itself, he wishes he had placed a bigger bet on the postelection rally.

"Sometimes you get these situations where it's almost a no-brainer where the odds are in your favor tremendously. There's absolutely no reason that everybody was saying 'if Trump wins everything is going to fall apart' — which is nonsense," Icahn said Thursday on CNBC's " Power Lunch ."

Icahn, who supported and advised Donald Trump during the campaign, explained that the president-elect had consistently said he would slash corporate taxes and roll back regulations.

But after Donald Trump's electoral college win, Dow (Dow Jones Global Indexes: .DJI) futures initially tumbled more than 800 points. The brief post-election plunge in the Dow was "completely, totally insane," Icahn said, adding that it made sense to "play the market."

The closely followed investor left the president-elect's victory party early to take advantage of the dip and bet about $1 billion on equities. Since then, the major indexes have continued to set many new highs.

While the rally may be a little "exuberant," Icahn said it makes sense because "all the things Donald's doing really point to a much, much better economy."

"I did buy a fair amount, I guess in perspective, but not nearly what I should have," Icahn said.