NAPERVILLE, Illinois, July 14 (Reuters) - Speculators last week established record net short positions in both Chicago corn and soybean futures and options as prices tumble further amid ample supply outlooks.

Money managers had reached record net shorts earlier this year, though new-crop CBOT corn and soybean futures have declined 10% and 7% since then, respectively.

The timing of funds' all-time bearish stances is historically unusual as they have come during a sensitive time for U.S. crop development, but the weather has been mostly yield-supportive.

However, data from the U.S. Department of Agriculture on Friday painted a much less comfortable picture of U.S. corn supplies than traders expected, which could justify a temporary price bottom or even some nearby short covering.

In the week ended July 9, money managers boosted their net short position in CBOT corn futures and options to 353,983 contracts from 336,538 a week earlier, almost entirely on new gross shorts.

In CBOT soybeans, money managers lifted their net short position to 172,605 futures and options contracts from 140,926 a week before, also dominated by new shorts. Some 92% of that position was built in the latest six weeks, one of funds' biggest soy selling streaks.

Money managers' previous record net shorts in CBOT corn and soybean futures and options were 340,732 and 171,999 contracts, respectively, set in the weeks ended Feb. 20 and March 5.

Prior to 2024, the record managed money net short in corn was 322,215 contracts on April 23, 2019, and for soybeans it was 168,835 contracts on May 14, 2019.

Combined open interest for CBOT corn and soybean futures and options of 3.08 million contracts is the third highest ever for the second week of July, behind 2018 and 2019. It is also about 6% above the five-year average for all weeks.

CBOT December corn and November soybeans both fell 3% in the week ended July 9, but corn popped 1.5% in the following three sessions while beans fell 1.4%.

December corn on Friday settled at $4.14-3/4 per bushel, down 17.6% since the start of 2024, and November beans settled at $10.65-1/4, down 14.5% so far this year.

SOY PRODUCTS AND WHEAT

CBOT December soybean oil reached three-month highs earlier in July, and futures rose as much as 4.6% in the week ended July 9 despite the overall 1% decline.

Money managers in that week slashed their net short in CBOT soybean oil futures and options to 17,018 contracts from 61,854 a week earlier and 108,483 two weeks prior.

That two-week net buying of more than 91,000 contracts, largely the result of short covering, is by far the most for any two weeks. The prior max was about 69,000 set in August 2016.

This comes amid an unwinding of long meal-short oil positions, and money managers through July 9 cut their net long in CBOT soybean meal for the fifth time in six weeks. December meal was down about 3% and funds' net long fell to 60,693 futures and options contracts from 73,459 in the week before.

Both meal and oil fell about 1.5% in the last three sessions, and meal futures hit contract lows on Friday.

CBOT September wheat was down 1.5% in the week ended July 9, though futures fell further in the following sessions and matched contract lows on Friday as USDA forecast a strong U.S. wheat crop.

However, money managers last week trimmed their net short in CBOT wheat futures and options by about 5,000 to 69,137 contracts. That is their second-most bearish wheat view for the date after 2016. Karen Braun is a market analyst for Reuters. Views expressed above are her own.

(Editing by Ros Russell)