"On Corn. Hello David, Eoin. I have noticed that your front month Corn chart might be showing September Corn instead of July Corn -- the latter having shown gains in the last two days. My own selfish reason for pointing this out, is that I have been fascinated by John Macintosh's research (thanks to Fullermoney) and it is looking like his prediction of a supply shortage this summer may be happening. (I also have a small long position in the ETF -- and yes I know you don't approve of these ETFs!). While I am here, thanks again for the fabulous service."

David Fuller's view Thanks for your kind words regarding the service. What makes it stand apart, if I may say so, is that by making Fullermoney interactive we all benefit from some of the Collective's vast experience, insights and knowledge - voluntarily contributed, of course.

The Chart Library follows Bloomberg's option of showing the most active contract, in terms of open interest, as the front month. Consequently, the continuation chart now reflects December data which is also the new crop, while July reflects the last of the expiring old crop contracts.

Normally, this is the best policy for traders and I note that July 2012 corn expires on 22nd June for IG Index positions. I have reproduced a July corn chart from Bloomberg for you and any other subscriber holding this position.

It shows today's prices shortly after the Chicago opening and the premium over September corn is about 80¢. With a supply squeeze, such as the inestimable John Macintosh has forecast, much of the action often comes in the last few days before the Chicago contract's delivery date.

Therefore a last minute scramble for corn from users who require immediate delivery could come too late for spread-bet traders but anyone holding CBT contracts would have a later expiry.

I do not know which corn ETF you hold but you are right; we do not like them, mainly because of costs, not least when contangos apply.