Chicago, N.Y. commodity exchanges in talks to merge.

NEW YORK, Jan. 28 Kyodo

CME Group Inc., the operator of the Chicago Mercantile Exchange, and Nymex Holdings Inc., the operator of the New York Mercantile Exchange, said Monday they are in ''preliminary discussions'' on CME's potential acquisition of Nymex.

The deal, if struck, is expected to reach about $11 billion, U.S. media reported.

The parties have agreed to a 30-day exclusive negotiating period.

Under the terms being discussed, shareholders of Nymex would receive $36 in cash and 0.1323 of a share of CME Group's common stock in exchange for each Nymex share, they said.

CME Group, created in July through the merger of the Chicago Mercantile Exchange and the Chicago Board of Trade, expects to maintain trading floors in the New York City metropolitan area.

The potential transaction also contemplates that Nymex will repurchase the 816 New York Mercantile Exchange memberships upon closing of the potential acquisition for an aggregate purchase price not to exceed $500 million, the two exchange operators said.

CME Group offers a variety of derivatives, including futures and options based on interest rates, equity indexes, foreign exchange and agricultural commodities.

Meanwhile, Nymex Holdings is the world's biggest market for energy-related commodities futures.