Brent crude plunged 10 per cent to a two-month low as investors bet that Democratic gains in the US midterm elections could accelerate efforts to end the Iran war and ease oil supply pressures. By Mia Gindis, Charles Gorrivan and Grant Smith Brent oil futures plunged 10 per cent to trade below $100 a barrel as investors wagered that a Democratic sweep in the US midterm elections could usher in a quicker.