Tether (USDT), the world’s largest stablecoin, crossed the $100 billion market capitalization mark for the first time on Monday evening, according to CoinMarketCap data. USDT has added $10 billion to its valuation since early December, fueled by bullishness about cryptocurrencies, particularly bitcoin. 

Tether’s market cap continued to rise above and below the $100 billion market cap level multiple times on Tuesday and was recently sitting at $100.1 billion, with 24-hour trading volume at $181 billion, a 55% increase from the previous 24-hour period.

Bitcoin has surged more than 45% over the last month and briefly reached an all-time high of $69,325 on Coinbase on Tuesday morning before dropping recently to the $62,000 mark.

USDT is the most popular stablecoin, ahead of Circle’s USDC and its current $29 billion market cap

The coin is pegged one-to-one with the U.S. dollar and is said to be fully backed by Tether’s reserves, which are seen as a protection against a stablecoin losing its peg. Those assets include U.S. Treasury bills, meaning Tether has benefitted from U.S. interest rates sitting at a 23-year high. 

While the price of USDT is supposed to remain at or close to $1, more investors purchasing the stablecoin drive up its market valuation. The market cap of Tether has risen steadily over time, but its increase picked up speed late last year as bitcoin (BTC) rallied ahead of the SEC’s expected approval of spot bitcoin exchange-traded funds (ETFs). That optimism helped carry the price of other cryptocurrencies along with it, further increasing the usage of Tether. Bitcoin prices have continued to rise following the actual launch on Jan. 11 of those ETFs, which have drawn in billions of dollars. 

Attestation Report

Tether released its fourth-quarter attestation report on Jan. 31, reporting a record $2.85 billion in net profit. The profit primarily came from interest earned on US Treasuries and the appreciation of its gold and BTC reserves. Tether also reported $5.4 billion in excess reserves, calculated by subtracting liabilities from total assets. 

USDT has long attracted controversy about the quality of its backing assets. In early February, JPMorgan analysts wrote in a research report that the increasing dominance of Tether over the past year is a negative for the broader crypto industry due to risks associated with its “lack of regulatory compliance and transparency.” 

Tether does have some support on Wall Street, however. Cantor Fitzgerald CEO Howard Lutnick defended the stablecoin in January during a Bloomberg TV appearance. Answering the commonly-asked question of whether Tether has as much money as it claims, Lutnick noted that Cantor Fitzgerald manages some of Tether’s assets and further replied, “From what I’ve seen – and we did a lot of work – they have the money they say they have.”