Nasdaq Stock Market Inc. has agreed to acquire the nation’s third-largest options market and the nation’s oldest stock exchange for $652 million in cash. Nasdaq expects the deal for the Philadelphia Stock Exchange to close in the first quarter next year, adding to the consolidation trend among the world’s exchanges.

“This strategic combination achieves our goal of diversifying our product and service offerings with attractive benefits to our trading clients while generating strong financial returns,” said Nasdaq President and CEO Bob Greifeld in a statement.

Nasdaq plans to maintain the Philadelphia Exchange’s structure, operating the electronic options trading platform alongside the options trading floor in Philadelphia.