A question for any folks here who have insight in the arb industry: I was quite suprised to see the 150tick spike down in YM on 23-June and AGAIN the next day. (See chart below). Other contracts were all well-behaved, the problem was only in YM. I would think that arbs (ES/YM, YM/DIA etc) would have kicked in and prevented this fiasco. And yet, it happened again on the very next day! I think it (150pt) must have been the largest deviation from fair value during RTH since I've watched the contract.