Twenty-one Contracts for Differences (CFD) firms have closed since 2025 following a crackdown by the FCA.
The regulator said it was concerned the firms were misusing their authorised status to mislead consumers.
It added that three other firms were currently in the process of cancelling their permissions.
The FCA said it was challenging CFD firms that carried out little UK business but use their authorisation as a badge to make linked overseas companies look more trustworthy than they really were.
The regulator warned that doing so creates the misleading impression that consumers are dealing directly with a UK-regulated firm and benefit from UK protections when they do not.
It said firms have faced a range of actions, including restricting their trading abilities, requiring independent reviews of their business and opening enforcement investigations in the two most serious cases.
Dominic Holland, director of sell-side supervision at the FCA, said: “Consumers need to know exactly who they're dealing with and what protections they have. When firms blur the lines between their UK-regulated activities and overseas businesses, we will step in. These closures show we're prepared to take action to protect consumers."
The FCA said consumers thinking about trading CFDs should remember that the products are complex and often involve high levels of leverage, meaning large losses can build up very quickly.
Before opening an account, consumers should check carefully that they are dealing with a UK authorised firm if they want the protections that come with FCA regulation.
Consumers should also use the FCA's Firm Checker to check they are dealing with a UK-authorised firm, and not an overseas firm with a very similar name to a UK firm. In the latter situation, UK regulatory protections are unlikely to apply.
CFDs are complex financial products used to speculate on the movement in prices on a wide range of assets. As a result, they carry a considerable risk of substantial losses.
Last November the FCA issued a warning to providers of CFDs after its review found that some firms were not meeting its Consumer Duty requirements. The regulator restricted any sales of CFDs to retail customers from 2019.
In March the FCA fined Dinosaur Merchant Bank Limited £338,000 for failings related to its handling of sophisticated CFD investments. The firm stopped selling CFDs in May 2025.
In July Influencer Lucy Beck pleaded not guilty at a court hearing to FCA allegations she was involved in unauthorised financial promotions of foreign exchange CFDs on social media. Her trial has been set for 12 June 2028.