the WTI official crude trade closes at 2:30pm each day. I think it closed down yesterday by $3.13, however USO continued to trade reflecting the WTI price after that which proceeded to trade down to $2.81. So some of today's rise was already baked into USO's opening price. Additionally, USO is now trading the May contract and not the April. The contango continues to tighten and you'll see more of that as the WTI contract officially switches on the 20th of March. Right now April is up $1.74 and May is up $1.22.