Impact of Indexers' Participation in Wheat Futures

As of the March 2 CFTC Commitment of Traders report, the commodity index net longs (swap dealers) comprised over 40% of the open interest in the CBOT wheat futures contract. This contrasts with commodity index longs of 25% of open interest on the KCBT and less than 5% of the open interest in wheat on the Minneapolis Grain Exchange.

This large chunk of the CBOT open interest cannot be accommodated by commercial sellers (farmers) alone. First of all, it is in addition to the normal demand from end users. Second, commercial sellers have been badly hurt by the lack of convergence of the futures to the spot market for Soft Red Winter Wheat, making increased exposure to the spot/futures basis very risky. So the "investor" interest from the commodity index funds has largely been offset by "speculative" shorts by non-commercial money managers.

It is clear that the CBOT contract will be strongly influenced by factors that affect broad commodity investment flows that pump up the long side and also by various pressures and risk controls that guide the money managers on the short side.
In contrast, the Minneapolis market features a more historically normal balance between commercial participants and speculators.

I think this explains why the CBOT is more responsive to developments outside the wheat markets and why the CBOT is more volatile on a daily basis.