I was looking at a multi year daily chart of CL and noticed that volume seemed to go from barely existent to full-on in a spike that lasted less than a month. This happened around Sept 2006 and I'm wondering if anyone knows what exactly happened around that time that made this contract so liquid all of a sudden ?

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Initial trading of NYMEX energy products on CME Globex, currently scheduled to begin in the second quarter of 2006, is expected to include side- by-side trading of NYMEX standard-sized and NYMEX miNY™ energy futures contracts for crude oil, natural gas, heating oil and gasoline with NYMEX's floor-based products during open outcry trading hours and when the NYMEX trading floor is closed. In the third quarter, all products trading on NYMEX ACCESS®, the exchange's after hours electronic trading platform, are expected to transition to CME Globex. Also under the terms of the agreement, CME Globex will be the exclusive electronic trading platform for metals products currently listed on the COMEX Division, with an anticipated third quarter launch.