Tesla also announced it would soon accept Bitcoin as a form of payment. Tesla board member Antonio Gracias may have been behind the investment.
Bitcoin soared 16% to a record high of $44,795.20 after the announcement and shares of Tesla jumped as much as 2%.
Spanish tech journalist Álex Barredo did some research and says Tesla acquired an estimated 42,069 bitcoins throughout January when the trading price was $34,893. These amounts would now have a net worth of more than $2.11 billion (profit of over $600 million).
Musk came under fire from experts for the way his Twitter announcement of the investment caused the bitcoin surge, with economist Dr. Nouriel Roubini saying his actions could be "criminal behavior."
"First take an individual position in bitcoin, pump the price up, and then say that Tesla has invested," he said of Musk's strategy in an interview with CoinDesk. "It's also irresponsible and it's market manipulation."
Vitor Constâncio, former vice president of the European Central Bank, said the "SEC will look into this."
Musk continuously pushed the corporate establishments buttons by posting vague meme or twitter messages. In late January, Musk went as far as to change his Twitter bio to the word "#Bitcoin" and posted, "In retrospect, it was inevitable." (bitcoin surge 15% as a result).
Musk simple mention of the cryptocurrency dogecoin, referring to it as "the people's crypto," created it to trade at 59% higher than the previous day.
Republican commissioner for the SEC Hester Peirce, who is supportive of bitcoin, told Reuters it was time for clearer guidelines on the use of cryptocurrencies.
"That adds to the urgency of us taking some sort of action in this area to provide more clarity," Peirce said of several companies including Tesla and Mastercard announcing they would accept the currency as a form of payment.