Chicago soybeans slid for a third consecutive session on Friday with poor U.S. weekly export data adding pressure on prices, but the market is still poised for a fifth week of gains, underpinned by forecasts for tighter supplies.

Despite a fall on Friday, corn and wheat are also on track for weekly gains, though prices are expected to remain anchored by abundant global grain supplies.

The Chicago Board of Trade's most-active soybean contract was down 0.9 percent by 1030 GMT to $10.62-3/4 a bushel, corn fell 0.6 percent to $3.86-3/4 a bushel while wheat dropped 0.3 percent to $4.66-1/2.

There was additional pressure on agricultural commodities stemming from a broad decline in Chinese futures.

"U.S. soybean exports were down and Chinese commodity markets are taking a hit today which is adding pressure on CBOT," said Kaname Gokon at brokerage Okato Shoji in Tokyo. "The market's upside momentum has reduced because short-covering by funds and commercials is over."

Chicago soybean futures surged more than 5 percent to their highest level in 18 months on Tuesday after the U.S. Department of Agriculture (USDA) forecast domestic stocks would fall more than most analysts expect by the end of the 2016/17 marketing year.

"(The recent price fall) does not affect fundamental elements, at the most can we talk about a technical correction and profit taking on this week's positions ahead of the weekend," French consultancy Agritel said about soybeans prices.

But traders speculate the USDA's June 30 acreage report could show a shift of about 1 million acres from corn into soybeans compared with the government's March 31 planting intentions report.

There could be support for soybeans as workers at the Rosario grains export hub in Argentina will go ahead with plans to start a strike on Friday to demand higher salaries.

The U.S. corn crop was 64 percent planted as of May 8, but rainy weather may have slowed progress since then. Soybeans can be planted later than corn, so delays tend to favor soybeans.

Wheat fundamentals remain bearish, with the USDA forecasting U.S. inventories will rise above 1 billion bushels by June 1, 2017, the most in 29 years.

Commodity funds were net buyers of CBOT corn and wheat futures contracts on Thursday but net sellers in soybeans.

Trader estimates of net fund buying in corn ranged from 13,000 to 17,000 contracts. They were net sellers of an estimated 7,000 to 10,000 soybean contracts and net buyers of 3,000 to 5,000 wheat contracts.