Dallas,TX-Based Oil & Gas Co HollyFrontier 4Q 2017 Net Income Was $557 Mil, Up 7 TIMES or Up $487 Mil From Its 4Q 2016 Net Income of $70 Mil ....................................................................................... HollyFrontier Received a US Federal Income Tax Benefit of $307 Mil in the 4Q 2017 Predominately From the Very Lucrative US Federal Income Tax Debt Forgiveness Feature in the Oil & Gas Co Favored US Trump Tax Cuts Act