Dow breaks above 24,000 mark as tax bill wins crucial support

Oil gains as OPEC agrees to extend output cuts

The Dow Jones Industrial Average pierced through the 24,000 mark for the first time on Thursday and the other indexes rallied on strong indications that President Donald Trump's tax-cut plan may get enough support for passage.

Republican U.S. Senator John McCain said he would back the tax legislation under consideration by the Senate, saying he believes it will directly benefit all Americans.

McCain, who had voted against the healthcare overhaul effort this summer, is considered a critical vote for the Republican effort.

The blue-chip Dow index has crossed four similar 1,000-point milestones this year on the back of strong corporate earnings, robust economic