Bitcoin continued to be under some pressure after a tweet from Tesla Inc. Chief Executive Elon Musk prompted speculation that the electric-car maker had sold, or would sell, its holdings of the cryptocurrency.While Mr. Musk later tweeted that Tesla hadn’t sold any bitcoin, the selloff demonstrated his power to shift cryptocurrency markets. Last week, he stated that Tesla had suspended accepting bitcoin as payment for its vehicles, citing concerns over its carbon footprint. Since then, the market value of bitcoin has dropped to roughly $835 billion from more than $1 trillion.Bitcoin traded as low as $42,102.35 overnight-before rebounding Monday afternoon $44,843.38. It is down roughly 30% from its record approaching $65,000 a month ago. Mr. Musk’s recent posts on Twitter have indicated that his views are having a substantial impact on the market.