CHICAGO, May 6 (Reuters) - Spot basis bids for soybeans shipped by barge to U.S. Gulf Coast terminals firmed, and corn bids held generally steady, as a downturn in oil prices on Wednesday weighed heavily on grain and oilseed markets, traders said.

• Chicago Board of Trade grain and soybean futures tumbled on Wednesday, giving up recent gains, as a decline in crude oil prices caused a flurry of long liquidation by managed commodity funds that had recently taken massive long positions on grains.

• Oil prices fell sharply to two-week lows on Wednesday as optimism grew about a possible end to the war in the Middle East. O/R

• Weakness in the U.S. dollar was seen as supportive, as it makes U.S. commodities more competitive globally, one broker said.

• At the Gulf, CIF soybean barges loaded in May were bid at 78 cents over Chicago Board of Trade July SN26 futures, up 2 cents from Tuesday. June loadings were bid at 83 cents over July futures, up 3 cents.

• FOB export premiums for Gulf soybean vessels loaded in June firmed up 2 cents at around 99 cents over July SN26 soybean futures, while loadings for May also ticked up 1 cent - offered at 108 cents over May SK26 futures.

• For corn, CIF barges loaded in May traded at 82 cents over CBOT July CN26 corn futures, and July loadings traded at 84 cents over July futures.

• CIF barges loaded in May were later bid at 81 cents over CBOT July CN26 corn futures, steady from Tuesday. June loadings were bid at 82 cents over July futures, also steady.

• FOB export premiums for Gulf corn vessels loaded in June were steady at around 104 cents over July CN26 futures.

• Empty barge freight rates were steady along key interior rivers, traders said. BG/US

• Meanwhile, cash basis bids for corn were mostly steady to firmer in the U.S. Midwest on Wednesday, rising at several ethanol facilities and one corn processing site as CBOT corn Cv1 futures tumbled from recent highs, spot checks showed.

• Brazil's soybean area is expected to post only marginal growth in the 2026/27 season due to higher production costs and risks linked to the El Nino climate phenomenon, Argus analyst Nathalia Giannetti said on Wednesday.

For displays of CIF basis, click on the codes in brackets:

U.S. CIF Gulf soybeans GRYM

U.S. CIF Gulf corn GRYN

U.S. CIF Gulf SRW wheat GRYO

U.S. CIF Gulf HRW wheat GRYP

For displays of FOB basis, please click on the following codes in brackets:

U.S. FOB Gulf corn GRZC

U.S. FOB Gulf soybeans GRZD

U.S. FOB Gulf SRW wheat GRZE

U.S. FOB Gulf HRW wheat GRZF

LINKS

Corn prices page: cpurl://apps.cp./cms/?pageid=corn-cash-market

Wheat prices page: cpurl://apps.cp./cms/?pageid=wheat-cash-market

U.S. barge freight BG/US

U.S. export sales estimates USDA/EST

U.S. grain export summary GRA/U

Brazil soybean export prices SYBS

Brazil corn export prices SYBX

Argentina grain prices GRA/ARG

Russia grain prices GRA/RU