Oil is the world's most traded commodity — and its price can swing $9 in a single day. On Wednesday, November 4, Brent crude fell $8.98, or 8.7%, to $94.62 a barrel; by Friday morning it had bounced back toward $100, with WTI near $91.50. The same week, both benchmarks were still heading for losses of around 12%. If you want to understand markets, you need to understand what moves oil...
