Billionaire investor Mark Cuban on Saturday questioned Donald Trump's sanity, saying he has decided to vote for Hillary Clinton because the Republican nominee has gone "off the reservation" and "crazy."

"Donald, initially, I really hoped he would be something different, that as a businessperson, I thought there was an opportunity there," the Dallas Mavericks owner and "Shark Tank" star told CNN while campaigning with Clinton in his hometown of Pittsburgh Saturday. "But then, he went off the reservation and went bat-s--t crazy."

Cuban, who once spoke fondly of the Republican nominee, also said that that now Trump "scares me."

While campaigning with Clinton today, Cuban used the Pittsburgh slang word, "jagoff," to express his dislike for Trump, and said: "I’m ready to tell you that I’m ready to vote for a true leader. I’m ready to vote for the American dream. I'm ready to tell the world that I’m here to endorse Hillary Clinton."