Global regulator the International Organisation of Securities Commissions has called for tighter rules on dark pools, coming at a time when the European Commission is reviewing the venues as part of a wider overhaul of its Mifid share-trading rulebook.

Dark pools are venues that allow institutions to trade large blocks of trades anonymously, ideally by being matched with corresponding orders. They are intended to prevent adverse price movements caused by the signals a large trade might give to the wider market.