The Second City of the US may not need two separate financial exchanges. The Financial Times has reported that Chicago-based CME approached smaller neighbour CBOE about an all-stock takeover. The deal would roughly value the company behind the Vix volatility index at $16bn. Even with a 20 per cent premium, CBOE would be a minnow in the consolidating world of exchanges.

CME’s own market worth is roughly $70bn. The business said it is not currently in acquisition talks. Given sharp new scrutiny on corporate consolidation, the window for a deal may already have closed. But combining the two exchange groups spawned by Chicago’s huge heft as a US trading hub would make a lot of sense

Global exchange groups have coalesced into just a handful of groups. Trading efficiencies created by deregulation and new technology have made combinations necessary. Lower friction has benefited buyers and sellers of securities alike.