Key takeaways: 

• In a tweet on Friday, the Tesla CEO revealed that he asked Gates if he was short-selling stocks of the electric carmaker.
• When investors short a share, they bet that the asset's cost will fall.
• It's not the first time the two guys have had a public debate.

Elon Musk has blamed Microsoft co-founder Bill Gates for shorting Tesla.

In a tweet on Friday, the Tesla CEO revealed that he asked Gates if he was short-selling stocks of the electric carmaker. When investors short a share, they are betting that the asset's cost will drop.

"I heard from numerous people at TED that Gates still had half-billion short against Tesla, which I asked him, so it's not precisely top secret," Musk said in the tweet.

He responded to a Twitter user's question on whether a screengrab of a presumed text conversation between the two billionaires was true.

The Tesla chief's answer was: "Yeah, but I didn't reveal it to NYT. They must have got it through friends of friends."

The account that asked about the text messages, @wholemarsblog, heavily boosts Tesla and Elon Musk and is among the few handles that Musk most interacts with on Twitter.