Elon Musk's performance on Tesla's earnings call could make people afraid to buy his stock — or his cars

It goes without saying that taking questions from Wall Street investment analysts about company earnings ranks as the least favorite duty of many CEOs, especially when the earnings numbers are as grim as, say, Tesla's.

But Tesla Chief Executive Elon Musk's performance on his conference call with analysts Wednesday, following the release of the company's first-quarter financial results, was in a class by itself. To mention the bottom line here at the top: It was enough to make people wary of buying his stock, and could even make people wary of buying his cars.

There's already evidence of the first phenomenon: Tesla shares were off by more than 8 percent in early Nasdaq trading Thursday. That brings the company's slump year-to-date to about