Corn futures are on track for their longest losing streak since June, as the market struggles to find fresh bullish catalysts to support a massive bet on higher prices from hedge funds.

Data from the U.S. Commodity Futures Trading Commission (CFTC) over the past two decades shows that money managers held a record net-long position in corn as of September 1. The previous week, prices had surged to a three-year high, driven by investors piling in on concerns over adverse weather hitting crop yields in the world's top corn producer and disruptions to grain flows in the Black Sea region.

That rally, however, pushed corn's 14-day relative strength index above 70, a level often seen as a signal that the market may be due for a pullback. Joe Davis, head of commodity sales at Futures International LLC, noted that such a large long position is difficult to sustain without fresh bullish catalysts, adding that funds have "no room left to add more." He also suggested the corn market may have formed a temporary peak.

On Wednesday, the most-active corn futures contract in Chicago fell as much as 1.1%, marking a fifth consecutive daily decline. Corn settled 0.8% lower at $5.2925 per bushel, while wheat and soybeans both slipped around 0.5%.