Oil ends at 3-year low after Saudis cut selling prices for U.S.

Crude-oil prices finished Tuesday at their lowest in three years, struggling in the aftermath of Saudi Arabia’s decision to alter oil prices sold to U.S. and Asian buyers.

sweet crude futures for delivery in December CLZ4, -0.21%  fell $1.59, or 2%, to settle at $77. 19 a barrel on the New York Mercantile Exchange. That was the lowest settlement for a front-month contract since Oct. 4, 2011. Oil has ended lower for four straight sessions, down 6.1% over the period.

December Brent crude LCOZ4, -0.52% settled at a four-year low. The December contract fell $1.96, or 2.3%, to end at $82.82 a barrel on London’s ICE Futures exchange. That was the lowest settlement for Brent since Oct. 21, 2010. Brent has also closed lower for four sessions in a row, losing 5% during the period.