warren buffett closely monitor whether u.s. president donald trump low corporate tax one rare time billionaire look washington help decide stock buy sell actual factor berkshire buffett chairman berkshire hathaway inc brka.n say tuesday interview cnbc television seldom 87 years ever factor buffett normally buy stock long term less focus tax issue ask think tax say think plenty get action side would take refer take gain realize losses say berkshire say end june 135 billion equity investments buffett mainly control hold long term conglomerate sit huge gain big investments american express co axp.n coca-cola co ko.n well fargo co wfc.n bet international business machine corp ibm.n fare less well buffett say berkshire annual meet omaha nebraska may would rather realize losses take gain expect rat fall might good strategy trump many congressional republicans succeed low top corporate tax rate 20 percent 35 percent buffett explain would feel kind silly realize billion gain pay 350 million tax congress low rate thus tax bill say investors sit hundreds billions dollars potential profit might think thing unclear whether republican-controlled congress pass tax bill trump sign buffett say unable overhaul affordable care act move forward infrastructure two president priorities expect know year end whether tax go would think republicans control house congress presidency would want shutout first year buffett say think get do buffett say success trump tax plan may affect stock investments