The Financial Conduct Authority plans to mandate full public disclosure of all trading data for London-listed shares, responding to concerns about unreliable liquidity measurements. Britain's top financial regulator says current reporting gaps create distorted views of market activity, potentially harming investor confidence.

Current rules let brokers withhold nearly half of UK equity trades from immediate public reporting. This exemption system allows firms to delay disclosing large orders, creating what the FCA calls 'drastic under-reporting' of actual trading volumes across London's £4 trillion stock market.

The proposed changes would eliminate most reporting delays, giving investors clearer visibility into price movements and execution quality. While some institutional traders worry about revealing proprietary strategies, regulators argue complete transparency will strengthen London's position against rival European exchanges.

Quick Fact: Current UK rules permit 45% of equity trades to avoid immediate public reporting.