Shares of MicroStrategy Inc. /zigman2/quotes/202561856/composite MSTR +1.53% sank 7.5% toward a four-month low in premarket trading Thursday, as the enterprise software company and bitcoin /zigman2/quotes/31322028/realtime BTCUSD +1.33% play is being weighed down by the selloff in the cryptocurrency. The company has been seen as a bitcoin play, because the company has been acquiring bitcoin and said it uses bitcoin as its primary treasury asset. The company disclosed that it spent $15.0 million to buy about 271 bitcoins on Thursday at an average price of $55,387 per bitcoin, including fees. The company said it now holds about 91,850 bitcoins, purchased for $2.24 billion at an average price of $24,403 per bitcoin. Bitcoin tumbled 8.1% early Thursday, after Tesla Inc. /zigman2/quotes/203558040/composite TSLA -0.04% Chief Executive Elon Musk surprised investors when he said the electric vehicle maker has suspended vehicle purchases using bitcoin. MicroStrategy's stock has run up 39.5% year to date, while bitcoin has soared 73.0%, the SPDR S&P Software & Services ETF /zigman2/quotes/203260274/composite XSW +1.13% has slipped 2.6% and the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.19% has gained 8.2%.