Citron Research's Andrew Left believes the run in shares of $MicroStrategy (MSTR.US)$ is not going to end well in the near term, and he's putting his money where his mouth is.

What To Know: Left on Thursday announced a new short position in software firm turned $BTC/USD (BTCUSD.CC)$ holding company MicroStrategy, despite remaining bullish on the trajectory of Bitcoin.

"$MSTR's volume has completely detached from BTC fundamentals," the short seller said in a post on X.

Benzinga has reached out to MicroStrategy for comment.

Left noted in the post that his firm was bullish on MicroStrategy in 2020 when the stock was trading below $250 per share on a pre-split basis. He predicted at the time that MicroStrategy shares could hit $700.

"Fast forward to today: $MSTR has skyrocketed to over $5,000 (adjusted) ... while Citron remains bullish on Bitcoin, we've hedged with a short $MSTR position," Left said. "Much respect to @saylor, but even he must know $MSTR is overheated."

From Earlier This Year: EXCLUSIVE: First He Bet Against GameStop, Now Andrew Left Is 'Long Bitcoin... Short Ether'

Left isn't alone in thinking the recent surge in MicroStrategy shares won't last. Seabreeze Capital Partners' Doug Kass announced a short position in MicroStrategy from $533.78 Thursday morning. At the time of writing, Kass had already covered at least 75% of the initial short. He closed half of his short position at $468 and another quarter of his initial position at $429.10.

MicroStrategy shares have accelerated to the upside in recent weeks as the company continues to execute on its strategy to accumulate billions of dollars of Bitcoin. The company announced plans at the end of October to raise $42 billion over the next three years to keep buying Bitcoin.

MicroStrategy held a total of 331,200 Bitcoin purchased at an average price of approximately $49,874 per coin as of Nov. 17.

MSTR Price Action: MicroStrategy shares were trading above $540 in pre-market trading Thursday morning. The stock pulled back at the open and continued to move lower after Left announced his short position. MicroStrategy shares were up 0.8% at $477.95 at the time of publication, according to Benzinga Pro.