Anton Peraire-Bueno, 24, and James Peraire-Bueno, 28, were arrested on charges of wire fraud and money laundering.
The US Department of Justice stated that the heist, which took place in April 2023, was "the first of its kind so far".
MASSACHUSETTS INSTITUE OF TECHNOLOGY GRADUATE
The brothers reportedly studied at the Massachusetts Institute of Technology (MIT), one of the most prestigious universities in the US, and used their "special skills" to bypass Ethereum's verification process for money transfers.
Local media reported that the brothers studied math and computer engineering at MIT.
"The defendants' scheme raised questions about the robustness of the blockchain system," said Attorney General Damian Williams.
Digital currencies such as Bitcoin and Ethereum are distributed through blockchain technology, and there is no central authority governing the system. Ethereum is considered the most popular cryptocurrency after Bitcoin.
The arrested brothers allegedly obtained Ethereum investors' cryptocurrency by fraudulently accessing pending private transfer transactions.
Investigators refer to the criminal activity as "the Exploit" (meaning 'exploitation' and also 'exploitation' and also 'exploitation').