It’s time for our monthly look at how the long-only commodity ETFs are performing versus simply holding the December futures contract and rolling annually.

Corn and natural gas bounced back from the May slide, although for the latter it was not enough to make it back into positive territory on the year. Crude oil, on the other hand, continued its downward trajectory. ETF underperformance against the December futures contract in crude oil and corn widened, while it narrowed for natural gas.

Futures trading is complicated, presents a risk of loss, and isn’t for everyone – especially since past market performance doesn’t necessarily indicate future results – but given the numbers, we’re left scratching our heads. Ultimately, we prefer a commodities investment strategy that can benefit from both rising and falling prices (like managed futures). But if you’re going to adopt a long-only strategy… we’ve yet to receive a good answer to the question: why invest in an ETF when you can just roll December futures contracts annually?

Read ‘em and weep: