CBOT corn futures sag lower on harvest pressure; USDA stocks data awaited

CHICAGO, Sept 29 (Reuters) - Chicago Board of Trade corn futures ended mostly lower in choppy trade, pressured by the expanding Midwest harvest, but uncertainty about quarterly government stocks data due on Tuesday kept a floor under prices, traders said.

• Most-active CBOT December corn CZ25 settled down 1/2 cent at $4.21-1/2 per bushel.

• Warm and dry weather over the U.S. Corn Belt promoted harvest progress over the weekend, and forecasts called for more of the same this week.

• Ahead of the U.S. Department of Agriculture's weekly crop progress report due later on Monday, analysts surveyed by Reuters on average expected the government to report the U.S. corn harvest as 20% complete, up from 11% a week earlier.

• Traders were adjusting positions ahead of Tuesday's USDA quarterly grain stocks report, which has a history of jolting futures markets.

• Ahead of the quarterly report, analysts surveyed by Reuters on average expected the agency to report U.S. September 1 corn stocks at 1.337 billion bushels, a four-year low.

• However, the estimate is above the 1.325 billion bushels that the USDA projected for 2024/25 corn ending stocks in its last monthly supply/demand report on September 12.

• Brisk export demand continued to underpin corn futures. The USDA reported export inspections of U.S. corn in the latest week at 1,527,145 metric tons, toward the high end of trade expectations for 1,100,000 to 1,600,000 tons. USDA/I

• Under its daily export sales rules, the USDA confirmed private sales of 135,660 metric tons of U.S. corn to Mexico and another 110,668 tons to undisclosed destinations.