Mumbai: Shareholders for the Chicago Board of Trade (CBOT) have approved plans to join forces with longtime rival, the Chicago Mercantile Exchange (CME, also called Merc), in an $11.9 billion deal. (See: CME bids $11.5 billion for CBOT v/s ICE''s offer of $11.4 billion)

The merger creates the world''s largest exchange but ends 159 years of independence enjoyed by CBOT, the world''s oldest commodities exchange.

The deal should close within days, the two exchanges said adding, the new firm operating the exchanges will be called CME Group, a Chicago Board of Trade company.

With the agreement to buy the Chicago Board of Trade sealed, CME, the biggest US futures exchange, will move trading to the CBOT''s art deco building.

CME''s purchase of the CBOT also marks a transition from pit-based to electronic trading. CME will be shifting pits to the CBOT building to preserves traditional face-to-face trading, which many traders still prefer. But, over a period, trading floors are expected to become obsolete as electronic trading takes over.

The Chicago Mercantile Exchange Trust, established in 1969 to provide financial assistance to CME financial settlement firms that become insolvent, owns the current trading floor. The trustees may decide in the next couple of months on the future of the trading-floor space, said Kassie Davis, the trust''s executive director.

CME''s acquisition of CBOT ended four months of negotiating that also involved attempts by the Atlanta-based Intercontinental Exchange Inc., to cut a deal of its own with a $11.4-billion offer.

A deal with CME became a certainty only after Merc raised its offer a third time to win over CBOT''s largest and most influential shareholder, Australia-based Caledonia Investments. Once that happened, the deal was all but done. ICE''s most recent proposal had been valued at a still-hefty $11.7 billion.

CBOT was founded in 1848 by 83 merchants at 101 S. Water Street. The board moved in 1865 to the Chamber of Commerce Building on the corner of LaSalle and Washington streets, only to have it destroyed in the Chicago fire of 1871.

Its next home was at LaSalle Street and Jackson Boulevard, which in 1885 was the tallest structure in Chicago and the city''s first commercial building with electric lights. The CBOT tore down the building and replaced it in 1930 with its current 45- story art deco home.

CME was founded in 1898 as the Chicago Butter and Egg Board at Lake and LaSalle streets in the Marine Building, a site that''s home today to a 27-floor office tower. The exchange''s longest stay was at 110 N. Franklin Street — now a vacant lot — from 1928 until 1972, when it moved to 444 W. Jackson Street. It''s been at 20 S. Wacker Drive since 1983.