CME will acquire London-based NEX in a transaction valued at £10 ($14) per share, consisting of £5 in cash and 0.0444 CME Group shares, based on CME's closing share price of $158.84 on Wednesday, the companies said in statements Thursday.
The transaction is expected to close in the second half of 2018, pending on the approval of regulators and NEX shareholders.
NEX is a provider of currency and fixed income platforms, and other over-the-counter (OTC) post-trade products and services.
The two companies said earlier this month that CME had approached NEX with a takeover offer, a move that triggered speculation that there could be rival takeover bids from other players like International Exchange Group or the London Stock Exchange.
As part of the acquisition, NEX shareholders will be entitled to receive £5 in cash for each NEX share and 0.0444 shares of CME Group.
"At a time when market participants are seeking ways to lower trading costs and manage risk more effectively, this acquisition will allow us to create significant value and efficiencies for our clients globally," CME Group Chairman and Chief Executive Officer Terry Duffy said Thursday.
"As one organization, we will be able to employ the complementary strengths of each company to serve a wider client base while diversifying our combined businesses across futures, cash and OTC products and post-trade services."
NEX CEO Michael Spencer will join CME's board of directors as part of the deal.
The transaction is expected to generate cost synergies of $200 million annually by the end of 2021, assuming the deal is completed this year.
The deal puts the U.S. derivatives giant in a prime position to shake up the U.S. Treasurys market. NEX provides one of the world's largest platforms for U.S. Treasurys trading, BrokerTec.