The shake-up of Europe’s "dark" trading landscape continued today as transatlantic exchange NYSE Euronext announced a tie-up with a Swiss dark pool, while Chi-X Europe overtook longstanding market leader, Liquidnet Europe, as the continent’s biggest dark pool operator.

Dark pools enable investors to trade large blocks of shares anonymously. Although the systems only account for around 1% of all European equity trades, they can be lucrative because investors are willing to pay more to keep their identities private.