Since its May 8 earnings report, Tesla Motors (TSLA -3.55%) has seen its shares soar. Great news had a lot to do with that, of course, but so did another factor: investors who had bet against the stock.

In this video, Fool contributor John Rosevear explains how investors who had sold Tesla's stock short actually contributed to its rise -- and whether the stock's impressive run is likely to continue for a while longer.