The International Organisation for Securities Commissions analyses the most significant technological developments and related micro-structural issues that have arisen in financial markets in recent years, notably high frequency and algorithmic trading, and their impact on market structure, participants’ behavior, price discovery and liquidity. The report recommends that: (i) trading venue operators should provide fair, transparent and non-discriminatory access to their markets, products and services; (ii) trading venues should have in place suitable trading control mechanisms (such as trading halts, volatility interruptions, limit-up-limit-down controls, etc.) to deal with volatile market conditions; (iii) all order flow of trading participants must be subject to appropriate controls, including automated pre-trade controls; and (iv) regulators should assess the impact on market integrity and efficiency of technological developments and monitor for novel forms or variations of market abuse that may arise as a result of technological developments.