This Is What Happens When The Market Remembers That David Einhorn Is Shorting A Stock

Sometimes it just takes a gentle reminder from a key player to get a stock moving.

On Tuesday the stock was athenahealth, the player was Greenlight Capital's David Einhorn, and the reminder was that Einhorn is short the company.

And here's what happened:

David Einhorn started speaking with CNBC's Scott Wapner outside of the annual Robin Hood Investor Conference around noon, and once he reminded viewers that he was still short athenahealth the stock started sliding.

Einhorn announced that he was shorting the healthcare technology company back in May at the Sohn Investment Conference.

"Jonathan Bush likes to compare athenahealth to Amazon because they both have websites," he said during his presentation - and followed that comment with brutal clip after clip of a giddy Bush ("yes, that Bush family," said Einhorn) talking about the company's wildly optimistic future.

Since then the stock is up 1.5%.