Legendary hedge fund manager and investor Carl Icahn just signed up for Twitter. In about 24 minutes, and a single tweet, he gained 1,190 followers. And so far, he hasn't followed anyone.

Icahn, 77, is famous for making large amounts of money, and most recently for having heated arguments with fellow hedge-funder Bill Ackman on live television. He also bought millions of dollars of Herbalife (NYSE:HLF), a stock that Ackman is trying to short.

Here's his first tweet:

For the full details of the Ackman-Icahn feud click here.