Atlas Pipeline Partners L.P., of Philadelphia, said Monday that it will pay $600 million for the operating assets of Cardinal Midstream L.L.C., a private Dallas company that operates natural gas processing plants and pipelines concentrated in Oklahoma.

Atlas said the acquisition, which is expected to close by the end of the year, would increase earnings guidance for 2013 by over 20 percent and distributable cash flow per unit by 3 percent to 5 percent in 2013.

The company will issue 9.25 million common partnership units to fund the deal. The announcement came after markets closed Monday. The company's units closed at $31.54, down $1.45 or 4.4 percent on the New York Stock Exchange.