On July 24, the NASDAQ OMX Group completed its acquisition of the Philadelphia Stock Exchange, renaming it NASDAQ OMX PHLX. The NASDAQ OMX Group reported that this acquisition positioned it to operate the third largest options market in the U.S., with NASDAQ OMX PHLX offering two market models: electronic and hybrid floor-based options trading. The NASDAQ OMX Group also reported that between these two market models, it would have a combined share of 17% of the U.S. equities options market.

http://ir.nasdaqomx.com/releasedetail.cfm?ReleaseID=324143