In a post by Arkham Intelligence on Saturday, the firm identified an estimated $25 billion in Bitcoin held in around 36 million wallets belonging to Coinbase and used for depositing and holding the tokens

Coinbase, the biggest crypto currency exchange in the US, is holding onto $25 billion in Bitcoin reserves, an amount that rivals the holdings of Bitcoin’s founder Satoshi Nakamoto.

In a post by Arkham Intelligence on Saturday, the firm identified an estimated $25 billion in Bitcoin held in around 36 million wallets belonging to Coinbase and used for depositing and holding the tokens. The biggest identified cold wallet holds around 10,000 Bitcoin, which is worth nearly $265 million as per the post.

Arkham’s estimate is based only on the wallets identified as being connected to Coinbase, but the company proposes that this amount is near the estimated amount held by Bitcoin’s founder.

This (amount) makes Coinbase the biggest Bitcoin entity in the world on Arkham, with nearly 5% of all BTC in existence, the firm wrote in a tweet.

Nakamato’s precise identity remains unknown fifteen years after the Bitcoin white paper appeared on an online messenger board for cryptographers. Like the enigmatic creator’s identity, the precise size of Nakamoto’s Bitcoin holdings remains a mystery.

Between January and July 2009, Satoshi is believed to have mined over 1 million bitcoins in total when Bitcoin’s value was lower than the value of a penny. At today’s value, this would equal more than $26 billion. If correct, this would make Nakamoto one of the biggest crypto whales today—but there has not been a definitive verification of his ownership of these wallets.

Trading in Bitcoin and Bitcoin pairs includes a considerable portion of Coinbase’s trading volume. In its latest quarterly earnings report, Coinbase said that trading in Bitcoin made up 40% of its total volumes, and around 39% in its transaction revenue.

Arkham estimates that the wallets it connected to Coinbase may be an incomplete figure based on the exchange’s stated financials. In Coinbase’s most recent 10-Q filing with the SEC, it estimated that the firm held $60.7 billion in customer assets and liabilities in Bitcoin.