Bitcoin's market capitalization reached $1 trillion on Friday as its price climbed to a new record high level just below $55,000. 

The cryptocurrency hit a new record high level of $54,790 at 11.42 a.m. EDT (1642GMT), after it surpassed the $50,000 mark Tuesday for the first time in history.

Bitcoin, the world's biggest virtual coin by market value, saw its price rise by 89% since Jan. 1 when it was $28,933. It has increased 660% since the beginning of 2020 when it was just $7,208.

The recent price surge looks different than a rally in 2017 when Bitcoin hit $20,000 before plummeting 80% the following year when most investors saw it as a bubble.

Latest rally came amid major US companies' recent announcements to shift assets to Bitcoin, and large Wall Street investment banking firms have started investing in it.

US Treasury Secretary Janet Yellen, on the other hand, warned investors Thursday saying they "should be very careful" in the markets.

Pointing out to the low interest rate environment, she said "While valuations are very high, price earnings, tight multiples tend to be high."

Yellen, who is the former Federal Reserve Chair, said she views Bitcoin as a "highly speculative asset."

"I think it’s important to make sure that it is not used as a vehicle for elicit transactions and that there’s investor protection ... so regulating institutions that deal in Bitcoin, making sure that they adhere to their regulatory responsibilities, is certainly important," she said./aa