(Reuters) - Amateur investors piled further into niche stocks on Tuesday, sending professional short sellers scrambling to cover losing bets, with GameStop skyrocketing for a fourth straight day, thanks in part to Elon Musk.

A man walks past a GameStop store in Austin, TX, U. S. October 3, 2015. REUTERS/Mike Stone/File Photo

His 11th tweet was to say that Tesla Inc (TSLA.O) stock would surpass Deutsche Bank's $420.50 price target. Shares were off by 6.0 percent at $566.85 Tuesday evening, after dipping into the $545.87 initial price.

But GameStop shares slipped on Wednesday, before ending 11.6 percent below where they started the day. Seconds after the short sell closed, GameStop chief investment officer Matt Nemerov said that while bullish on Tesla shares, it did not bear out the Tesla car restocking plan.

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The stock effort among amateur investors sprang from Musk's reaction to testifying before the U.S. Senate Sessions hearing two weeks ago, in which he said he took bribes from corrupt New York officials and other members of the auto industry to support a deal and support their "planet friendly policies."

Musk previously stated he would not personally benefit from them, and said he postponed his, and the firm's, expected 2015 earnings announcement for an additional six to nine months "to further ensure my integrity."

GameStop's shares fell to more than $520 after the stock culician began deploying his most successful tactic - himself. The SEC ultimately decided not to pursue the matter further, a pretty standard outcome for the SEC in an amateur stock bounce.

Salient Investors' Institutional Research Fund was the biggest small investor in GameStop stock at $976.63; it fell off by about 5.7 percent, a day after GameStop raising stock this time.

How did Nemerov react to the setback? "Right after the sell-off, Mark (Johnson) and I were on a conference call kind of laughing and figuring out how to replace the $2.5 million gallon of gas presumably in my coupe in which we are now stranded," Nemerov told Reuters.

Adjusting for volatility, GameStop's monthly gain of 21.4 percent is the most among stocks tracked by FactSet, beating the 2.8 percent gain in Donald Trump's S&P 500 index's 2,017-share G.O.P.

By comparison, Shares of fellow trade publication Visa Inc (V.N) fell by 3.6 percent after an analyst said Visa was outbuying rival MastercardTM in the credit card business
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