FORTUNE -- Apple's (AAPL) shares moved sharply from the red to the green Tuesday afternoon. There are a couple theories why, but the leading contender is the rumor on Twitter posted just before the stock popped by Douglas Kass, president of the Seabreeze Partners hedge fund, frequent contributor to The Street and regular guest on CNBC.
Kass, whose tweets are a matter of public record, has 55,456 followers on Twitter.
The first in the selection at right was posted at about 1:30 p.m. Eastern and the second seven minutes later, corresponding precisely with the vertical rise in Apple's fever chart .
We've been hearing quite a lot from Kass since The Street published his The Bear Case for Apple on Sept. 24, 2012, the first trading day after Apple hit its all-time high of $705.06. (See here, here and here.)
It would be a mistake to credit him with the subsequent five-month, 38% drop in Apple's share price that lopped $250 billion off the company's market value.
But it's hard not to pin Tuesday's action on Kass' Twitter posts or to see how he profited from them. The stock was down. He tweeted the split rumor. The stock went up. He sold shares while tweeting that his rumor was baseless.
As you can see from the exchanges that followed, he took some heat for what seemed on the face of it to be self-serving manipulation.
In his defense, Kass says the split rumor had been out for days or weeks before he posted it. To critics calling for his head, he suggests that they bone up on securities law.
For the record, the purposeful spreading of false information in connection with the purchase or sale of securities violates several sections of the Securities and Exchange Act.
That "purposeful" bit is the loophole. The trick, should the SEC choose to look into the incident, would be to prove that Kass knew the rumor was false when he posted it.
Kass' handle on Twitter is @dougkass.
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