IC Markets is the largest forex broker by trading volume with over $774 billion in forex trading activity in the third quarter of 2021 alone. The largest broker may change depending on the amount of time used to calculate size. However, the largest brokers have the most assets under management, the most clients, and the highest market capitalization (valuation for public companies). All of these factors should be considered when determining the size of a forex broker.

https://www.icmarkets.com