The United Kingdom Gambling Commission fined the William Hill-owned casino Mr Green with 3 million US dollars. The reason for the fine was, according to the Commission, anti-money laundering and responsible gambling shortcomings that the casino was guilty of.
The UKGC investigated the company and concluded that Mr Green did not adequately check the source of funds its customers use for depositing. The authorities apparently “uncovered systemic failings in respect of both Mr Green's social responsibility and anti-money laundering controls which affected a significant number of customers across its online casinos”.
That, in turn, resulted in that significant fine the company was subjected to.
The UKGC doesn’t play around at all, it seems. It’s probably for the best, I think.