Oil prices crumbled another 5 percent to around $43 a barrel on Thursday, suffering the biggest two-day slide since the Gulf War after a rise in U.S. heating oil stocks triggered furious selling. U.S. crude oil futures fell $2.34 a barrel to $43.15 a barrel after striking a 12-week low of $42.50. London Brent dropped $2.21 to $40.10, the first fall below $40 a barrel in three months. After U.S. crude plunged $3.64 Wednesday, the combined two-session fall is the fourth biggest in the New York Mercantile Exchange's history and the steepest since January 1991 during the first Gulf War, according to Reuters figures. Big-money speculative funds and local traders in New York and London have bailed out in force, pulling down prices now $13 below their October all-time high, although still 30 percent up from the start of the year. "There's been a lot of liquidation. It could be that people think it's been a great party but it might just be over," said Peter Gignoux, senior oil advisor for GDP Associates in New York. Lean U.S. stocks of heating fuel are rising as U.S. refineries ramp up runs after maintenance and unusually mild early winter weather in the U.S. Northeast limits demand. --More 2316 Local Time 2016 GMT