U.S. crude-oil prices slid below $30 a barrel Monday, tumbling to a fresh four-year low with analysts expecting the coronavirus and a Saudi-Russia price war to result in a glut of fuel. U.S. crude futures dropped 9.5% to $28.70 a barrel on the New York Mercantile Exchange, continuing a recent rout that has slashed prices by more than half for the year as the coronavirus dents travel and fuel consumption. Brent crude, the global gauge of oil prices, fell 11% to $30.05 a barrel. …