In Hong Kong, forex brokers and other financial services companies are regulated by the Hong Kong Securities and Futures Commission (SFC). This is a regulator that is known to take its job very seriously, with strict licensing requirements and higher minimum capital requirements than what is found in most other offshore jurisdictions.
Hong Kong-regulated forex brokers often use the city as a base for their business in China and Asia in general. Although the city is technically a part of China, it has its own laws and financial regulations that make it far easier to operate a brokerage there than in Mainland China.