The operator of Seychelles-based cryptocurrency exchange OKX, Aux Cayes FinTech, has pleaded guilty to violating US anti-money laundering laws.

The firm admitted to running an unlicensed money transmitting business and will pay about US$505 million in fines and forfeited fees, according to the US Department of Justice.

The plea was made before US District Judge Katherine Polk Failla in Manhattan on Feb. 24.

Prosecutors said that from 2018 to early 2024, OKX facilitated over US$5 billion in suspicious transactions and criminal proceeds.

Despite an internal policy barring US users, the exchange allowed them to conduct over US$1 trillion in transactions.

The company also allegedly helped users evade restrictions, including advising a customer to use false identification.

OKX is ranked as the fourth-largest cryptocurrency spot exchange globally, according to CoinMarketCap, which assesses traffic, liquidity, and trading volumes.