Investigators, supported by the Metropolitan Police and West Yorkshire Police, searched properties near Bradford and Herne Hill.
The law enforcement agency said the men – one in his 30s and the other in his 40s – were arrested on suspicion of multiple fraud and money-laundering offences.
It said the action follows the collapse of a firm which raised 28 million US dollars – equal to £21.4 million – from investors.
In the latest update on Monday, November 24, the Serious Fraud Office said the arrested individuals have since been released under investigation.
Last Thursday, the law enforcement agency appealed for information from investors in a cryptocurrency scheme called Basis Markets.
It said it launched the investigation into the “suspected fraudulent scheme”.