>A Cboe spokesman told CNBC: "We take our regulatory responsibilities and the oversight of our markets very seriously. This letter is replete with inaccurate st

>A Cboe spokesman told CNBC: "We take our regulatory responsibilities and the oversight of our markets very seriously. This letter is replete with inaccurate statements, misconceptions and factual errors, including a fundamental misunderstanding of the relationship between the VIX Index, VIX futures and volatility ETPs, among other things. As a result of these errors, we feel the conclusionary statements contained in this letter lack credibility."