Stocks powered through a volatile session caused by Greece uncertainty and closed higher, ahead of Thursday's jobs report. All three major stock indexes posted gains. But trading was choppy, as Greece Prime Minister Alexis Tsipras urged citizens in a Wednesday speech to vote against austerity proposals in the referendum on Sunday ‘to open a new bright page in our history.’ He denied the referendum is a vote about exiting the eurozone and said a ‘no’ vote will give him more leverage in negotiations with creditors. Plus, crude prices saw a sharp decline of 4.2 percent to $56.95 a barrel, after U.S. crude inventories jumped by 2.4 million barrels last week, according to the Energy Information Administration. Analysts were looking for a decline of 2 million barrels. The U.S. Justice Department filed an antitrust lawsuit to block Stockholm-based Electrolux's $3.3 billion acquisition of General Electric's (GE) appliance unit. That deal was announced last September. Reports from the Associated Press said the Department of Justice is investigating airlines for collusion, but did not specify which ones are under scrutiny, though United Airlines confirmed it was contacted by the Department. United Continental Holdings (UAL) fell over 2 percent, while shares of American Airlines Group (AAL) slumped almost 3 percent. Delta Air Lines (DAL) decreased 2 percent.