Private Bitcoin transactions using the CoinJoin method have tripled since 2022, driven by significant Bitcoin accumulators, according to CryptoQuant. These major players, or whales, are associated primarily with spot Bitcoin exchange-traded funds, MicroStrategy, and custodial wallets. CryptoQuant’s CEO, Ki Young Ju, refutes the notion that these transactions are largely used by hackers for laundering stolen funds. Instead, Young Ju points out that the $2.2 billion in losses from crypto hacks reported by Chainalysis in 2024 constitutes only a small fraction—0.5%—of Bitcoin’s $377 billion in realized capital.
CoinJoin transactions obscure the ownership of unspent transaction outputs by pooling inputs and outputs from multiple parties. Despite public disclosures by listed firms, there are still unidentified Bitcoin whales who have amassed up to 420,000 Bitcoins, valued at more than $40 billion. This has led to speculation about whether a nation-state might be quietly building a Bitcoin reserve or if a sanctioned country is acquiring Bitcoin to mitigate risk.
The potential misuse of CoinJoin transactions has caught the interest of law enforcement worldwide. In the United States, authorities arrested the founders of the Samourai Wallet, a privacy-focused Bitcoin service, and shut down its website in April. The U.S. Department of Justice stated that Samourai’s CoinJoin feature facilitated $2 billion in unlawful transactions and enabled over $100 million in money laundering. Similarly, Dutch authorities arrested Alexey Pertsev, developer of the crypto mixing tool Tornado Cash, who was found guilty of money laundering.
