The deal, which will see CME's parent company pay $8 billion for CBOT, will mark the combining of the US's two largest futures exchanges.
Merging the two exchanges will also confirm Chicago as the major centre for derivatives trading in the US, observers have said.
Commenting on the announcement of the merger, David Easthope of Boston's Celent financial research firm told the Los Angeles Times that it marked the current boom in derivatives trading.
"The derivatives market is growing much faster than the equities market, and it's more profitable," he said.
"This creates the biggest derivatives powerhouse that there is."
The move comes as exchanges across the world seek to consolidate their positions, protect themselves against global competition and cut costs.