The Securities and Exchange Commission (SEC), the US regulator, has proposed a radical overhaul to the structure of the US market, despite dissent among commissioners about how best to modernise the system.

The most controversial proposal related to the trade through rule, which compels brokers to execute a trade at the best price. The SEC has been under pressure from large US fund managers to abolish the rule that currently applies only to stocks listed on the New York Stock Exchange (NYSE), which can slow down execution and impact prices.