The Chicago Mercantile Exchange, the world’s largest futures exchange group, has launched a bid to buy the New York Mercantile Exchange, the US energy and metals exchange, after exclusive talks between the two markets finished on Saturday.

The CME, which confirmed it was in exclusive talks with Nymex on January 29 before extending the negotiation period to March 15 a month later, has launched a stock and cash bid valuing the exchange at about $9.3bn (€6bn).