May 1, 2012. Energy Transfer Partners LP is discussing a pipeline project with its counterpart at Sunoco Inc. Before the talks were over, it decided to buy the whole company for $5.3 billion. The agreement to purchase Sunoco is the third time it is swept up a rival pipeline operator in the past 13 months, paying a total $12.6 billion in cash and shares. Each deal has been calculated to expand Dallas-based Energy Transfer's footprint and business mix, transforming it from a regional natural-gas pipeline operator to a national shipper of gas, crude and refined fuels.