Oil prices tumbled over 4% today, reaching a 3-year low as trader sentiment continued to sour ahead of tonight's highly anticipated U.S. Presidential debate between Donald Trump and Kamala Harris, with bearish sentiment sinking to multi-year lows as traders continue overreacting to any negative development and ignoring relatively healthy fundamentals. Indeed, hedge funds and other money managers have turned the most bearish on crude ever since the CFTC started to publish information on market positioning, with speculative positioning in crude…