December corn futures settled 1 cent lower at $5.22 per bushel on Sept. 29, 2026, while November soybeans gained 9.5 cents to $12.9775 and wheat contracts diverged, as traders repositioned ahead of USDA's quarterly Grain Stocks report due Wednesday.

The report will set new estimates of corn, soybean and wheat inventories as of Sept. 1, and the numbers carry direct consequences for basis levels, storage decisions and producer marketing plans with combines already rolling across the Midwest. Analysts expect USDA to report 1.911 billion bushels of corn stocks, up roughly 360 million bushels from 1.551 billion a year earlier. Soybean stocks are projected at 321 million bushels, down 4 million from last year, and wheat stocks at 1.857 billion bushels, a decline of 277 million.

Those divergent supply expectations frame the split trading in Chicago. Corn futures briefly moved higher before technical selling erased the gains; March corn slipped half a cent to $5.36. The session traced a volatile arc — an early decline, a sharp recovery, then renewed pressure late in the day.

Crop development data adds context. USDA rated 57% of U.S. corn good to excellent, unchanged on the week, with 26% fair and 17% poor or very poor. Pennsylvania, Iowa and Minnesota posted some of the strongest combined good-to-excellent ratings among major production states. About 96% of corn is dented against a five-year average of 95%, 72% is mature versus 71%, and harvest reached 18% — matching the five-year pace but landing at the bottom of analysts' 18%-21% range.

Soybeans firm on slow harvest pace

Soybeans moved the opposite direction. November futures climbed 9.5 cents to $12.9775, and January gained 9.75 cents to $13.1275, supported by a slower-than-expected harvest and technical buying. Futures trended higher through most of the session before pulling back from the intraday peak.

Soybean ratings held at 58% good to excellent, with 29% fair and 13% poor or very poor. About 75% of the crop was dropping leaves, matching the five-year average. Harvest reached 17% — on the historical average but short of trade expectations of 18%-23% — and that lag lent support to futures ahead of the report. Within the complex, December soybean meal eased 0.11% while December soybean oil gained more than 1%, a divergence that matters to crushers, livestock producers and renewable fuel markets.

Wheat splits as planting trails normal pace

Wheat delivered a mixed performance. December Chicago soft red winter wheat gained 4 cents to $6.9775 — staging a pronounced recovery late in the session — while December Kansas City hard red winter fell 2.75 cents to $7.43.

Winter wheat planting jumped from 17% to 27% as of Sept. 27, but that still trails last year's 32% and the five-year average of 34%. Eight percent of the crop had emerged, up from 2% a week earlier.

International demand is shaping the U.S. wheat balance too. South Korea issued a tender for 3.7 million bushels of U.S. wheat, with likely shipment in November and December. European Union wheat exports for the 2026/27 marketing year reached 250.2 million bushels through Sept. 27, with EU production estimates holding at 4.564 billion bushels — competition U.S. exporters will face alongside tightening domestic inventories.

Weather adds uncertainty to harvest logistics

Forecasts call for 2 to 3 inches of rain or more in parts of the Plains and Midwest between Wednesday and Saturday, with Texas, Oklahoma, Kansas, Iowa and northern Illinois among the areas expected to receive the heaviest totals. Those rains could temporarily slow fieldwork and grain movement through the supply chain. Conditions are then expected to turn drier than normal across much of the Corn Belt from Oct. 6-12, while above-normal temperatures cover the western half of the country.

All eyes now turn to Wednesday's Grain Stocks report. With corn supplies expected to rise year over year while soybean and wheat stocks tighten, any surprise in the numbers could quickly reshape futures, basis levels and the market's view of U.S. grain supplies heading deeper into harvest.