I have seen marketing materials advertising ETCs on single commodities futures to track the commodities performance (or better the corresponding front month future contract) as Delta 1 products. However, as time goes by the underlying future contract needs to be rolled, which means we leave the current (soon to expire) contract and enter into the upcoming front month contract. This in turn is likely to change the participation rate (the number of underlying future contracts which the ETC holds). Is it correct that the delta of the ETC equals the participation rate and, thereby, could be quite different from 1? What other risk factors can be relevant here from a hedging perspective?