Pioneer Natural Resources Company (NYSE:PXD) is in talks to buy Parsley Energy, Inc. (NYSE:PE), according to people familiar with the matter, as a wave of consolidation takes hold in the beleaguered oil patch. The two companies, shale producers that operate in the Permian Basin of Texas and New Mexico, are discussing an all-stock deal that could be completed by the end of the month assuming the talks don't fall apart, the people said.