Somewhat quietly, the iPath Bloomberg Coffee Subindex Total Return ETN (NYSEArca: JO) is one of this year’s best-performing commodities exchange traded products and much of JO’s bullishness has been accrued in recent weeks.

Now up more than 18% year-to-date, JO, the larger of the two coffee exchange traded notes (ETNs), is higher by more than 5% over just the past week.

Concerns over coffee supplies out of Brazil may have triggered a short-squeeze in the futures market, forcing large bearish traders to close out positions and buy into the rally. Managed money turned net short on coffee after a selldown of net 21,000 lots over two weeks, Agrimoney reported.

Related: Coffee ETN Pullback Could Spell Opportunity

Brazil is the world’s largest coffee producer and the winter there was colder than expected this year. The impact of more frost than expected in Brazil’s coffee-growing regions still is not clear on this year’s coffee crops.

Supply is always a critical part of the discussion regarding any commodity and the same is true of coffee. The good news for coffee bulls is market observers are forecasting a major supply deficit.

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