Consolidation in the U.S. shale industry is accelerating, ratcheting up pressure on oil and gas producers to gobble up smaller rivals, analysts and executives said.  Pioneer Natural Resources Co, one of the largest independent shale operators, joined the ranks of dealmakers as it announced on Tuesday a low-premium $4.5 billion buyout of Parsley Energy Inc. The coronavirus pandemic has slashed oil demand and forced struggling shale producers to cut costs. Crude prices have slid about a third this year but drillers still must invest to maintain the same rate of production as the output of existing shale wells decline. Global majors are not likely to step in, so analysts expect the dwindling universe of notable producers to […]