NAPERVILLE, Illinois, March 14 (Reuters) - Speculators' selling of Chicago grain and oilseed futures in the last week of February far surpassed market expectations, led by a massive reduction in corn bullishness.

The U.S. Commodity Futures Trading Commission's Commitments of Traders (CoT) report has been on delayed release for over a month following a data interruption, but it published data for the week ended Feb. 28 on Tuesday afternoon.

That week was very volatile in CBOT futures with corn and wheat both down more than 7%, soybeans down 4%, soymeal down 3% and soyoil down close to 5%. Corn posted multi-month lows that week and wheat fell to the lowest in a year-and-a-half.

In the week ended Feb. 28, money managers slashed a record 147,293 CBOT corn futures and options contracts from their net long position, which fell to 68,635 contracts, the lowest since September 2020. The prior weekly record for net corn selling was 103,683 contracts in mid-March 2017.

Trade estimates had pegged the week's fund selling in corn futures at 47,000 contracts, and the actual futures-only selling neared 151,000 contracts, also a weekly record.

In corn futures and options, money managers' weekly move included a record dumping of gross longs, more than 80,000 contracts compared with the prior high of around 66,000 set in June 2016. They also added nearly 67,000 gross shorts, the most for any week since August 2019.

Managed money net selling in CBOT wheat futures and options through Feb. 28 was just under 20,000 contracts and due entirely to new gross shorts. The resulting net short of 91,641 contracts is funds' most bearish since January 2018.

Through Feb. 28, money managers cut their net long in CBOT soybean futures and options by 59,399 contracts to 129,610, a two-month low. That was their fourth largest soy selling week and the largest since November 2019's record of 61,393 contracts. Exiting of longs was prominent.

Trade estimates had funds selling 35,500 CBOT wheat futures and 37,500 soybean futures in the week ended Feb. 28. Open interest in CBOT corn, soybean and wheat futures and options all declined 8% during that period.

Money managers have held net longs in CBOT corn and soybeans since September 2020 and April 2020, respectively, and in CBOT soyoil since June 2020. Their recent bullish streak in soymeal began in November 2021 and they have been bearish CBOT wheat since July.

The latest moves were less extreme in soy products. Through Feb. 28, money managers reduced their net long in CBOT soymeal futures and options to 139,971 contracts from a record 154,141 a week earlier.

They also reduced their net long in CBOT soyoil to 28,093 futures and options contracts from 34,301 in the prior week, but the new position was not a recent low. However, funds may be flat or short soyoil in real time.

Between Feb. 28 and March 14, moves in most-active CBOT futures were as follows: wheat -1.3%, corn -1.5%, soybeans +1.0%, soymeal +3.0%, soyoil -6.4%. Over the same period, open interest in futures only moved higher for all five contracts, though to varying degrees.

Daily fund estimates collected by Reuters suggest that from March 1 through March 14, commodity funds were net sellers of 10,000 CBOT corn futures and 16,000 soyoil futures. Funds were seen as net buyers of 2,500 CBOT wheat futures, 4,000 soybean futures and 9,000 meal futures.

If CFTC continues releasing CoT data in the two-per-week fashion, the data will be current by March 24. Karen Braun is a market analyst for Reuters. Views expressed above are her own.

(By Karen Braun; Editing by Christopher Cushing)