Means that they have short-selled Tesla stock. Simply put, they are betting on the Tesla share price to fall. Edit: Together with the highly dubious "statistic

Means that they have short-selled Tesla stock. Simply put, they are betting on the Tesla share price to fall. Edit: Together with the highly dubious "statistical" analysis they did, this COULD suggest that the article is intended to create doubts about Tesla and thus drive the stock price down. However, this is of course speculation.