Monday brought a fair few surprises to agricultural commodity investors.
And not just in grains.
Sure, the scheduled highlight of the day was the US Department of Agriculture's release of its quarterly grain stocks report, a data series which has a habit of causing large price movements, and did not disappoint this time, driving corn futures to a three-year low.
But it was a lower profile calendar item, the expiry of New York's October raw sugar contract, which actually caused a bigger move, in percentage terms.
The October contract soared 3.6% to 17.48 cents a pound, very nearly reversing its collapse of the last session, on a jump attributed largely to last-minute short-covering, as relatively large open interest noted last week was found to relate to investors betting on price falls.
Expectations, or not, of a huge delivery, with sums of 1.5m tonnes being mentioned, were also seen as playing role, with Brazil's real chipping in by recovering 1.4% against the dollar, so making ags in which Brazil is a major player, such as sugar, more expensive in greenback terms.
New York's best-traded March raw sugar lot added 2.3% to 18.14 cents a pound, much to the relief of hedge funds which have built up a substantial net long in futures and options.
That was a far cry from the fate of Chicago corn for December, which slumped 2.8% to $4.41 ½ a bushel, the lowest finish for a spot contract in three years (and also spelling gains for hedge funds, which have a record net short in the grain).
The primary cause was a USDA stocks report which pegged domestic inventories at the close of 2012-13, at the start of this month, at 824m bushels – far higher than the figure officials have been working on (of 661m bushels) and the number (of 681m bushels) that investors had expected.
The number implied corn feed use during the quarter of 260m bushels - a record low - according to CHS Hedging.
And nor was there any excuse this time from the idea of an early harvest meaning that some new crop supplies were counted in to given an artificially high estimate for a figure which is meant really to show just how much old crop was left over at the end of the season.
'Yields are a surprise'
As an accessory in corn's decline, talk of the US harvest continues to be upbeat.
"The trade is now openly discussing a corn yield of 157-158 bushels per acre and soybeans at 42 bushels per acre," above the 155.3 bushels per acre the USDA has factored in, US Commodities said.
At Allendale, Paul Georgy, after a weekend crop tour of Illinois and Missouri, said that farmers "reiterated the same thing we were hearing all week.
"Corn yields are a surprise with most yields 10-30 bushels per acre more than what they were expecting. Clinton County, Illinois corn yields were the best they have ever harvested."
Harvest activity is expected to pick up pace this week too, from the 13-16% expected in separate crop progress data due from the USDA later.
"The favorable weather over the next four-to-five days should allow harvest to get in full swing, although producers are concerned about the slow dry down," Mr Georgy said.
With a fast harvest speaking of bountiful supplies that, and in particular the stocks report, more than offset price-positive influences from US export sales, which picked up last week to 21.9m bushels, from 18.0m bushels the week before, and from ideas that farmers will hold on to corn at current price levels.
"The trade has little confidence that producers are going to be willing sellers of corn at harvest," Benson Quinn Commodities said.
Some of the same points for corn applied in soybeans too, with harvest pressure weighing on the oilseed, along with a higher stocks figure than investors had thought.
The USDA pegged domestic soybean inventories as of the start of the month at 141m bushels, up 16m bushels on the figure it had been using, and a factor it explained by saying that last year's drought-affected harvest had been bigger than thought.
(That upgrade also has a negative read through to this year, in signalling that moisture-deprived crops benefited more from late rains than had been thought.)
US export sales were, at 14.3m bushels, down from the 16.8m bushels the week before, and well below the 41.8m bushels seen in the same week last year.
As an extra negative for values, Abiove, the Brazilian oilseeds industry group, lifted its estimate for domestic output of soybeans in 2013-14 by 4.4m tonnes to 86m tonnes.
While lower than the 88m tonnes at which the USDA has the figure, on exports, where Brazilian supplies really count in affected US prices, Abiove was more generous, pegging them at 44m tonnes, above Washington's 42.5m-tonne figure.
Soybeans for November closed down 2.8% at $12.82 ¾ a bushel, the contract's lowest close in six weeks (and down 9.0% from a late-August high).
At Allendale, Rich Nelson said that "no-one expected a bull market to last past February though with the coming South American harvest next spring.
"Today's report has eliminated the chance for a rally to $14 a bushel. It suggests $12.50 a bushel for a November soybean target in the short term."
Ominously for chart watchers, the contract closed below its 50- and 75-day moving averages for the first time since then, and nearly surrendered its 100-day moving average too.
More bullish on stocks
It was left to wheat, again, to give bulls some hope - and even then it was down to Kansas City-traded hard red winter wheat, rather than Chicago soft red winter wheat, to do the work.
The USDA stocks data for wheat as of September 1 was more price-positive, at 1.85bn bushels, well below forecasts of 1.91bn-bushel figure.
However, the impact was nuanced by a separate report revising US production estimates for small grains which did not prove the formality that had been expected.
Rather than making small, largely negative, changes to its estimates for the harvests of the various wheat classes, the USDA upgraded most of the data – offset by a 47m-bushel downgrade, to 744m bushels, in the estimate for output of hard red winter wheat.
Russian prices rise
US exports showed signs of tailing off last week, at 33.0m bushels, down from 43.1m bushels the week before, which counteracted some ideas of resilient demand, although Tunisia tendered for milling wheat.
Still, it is not as if wheat in Russia, typically a price leader, is enhancing its competitiveness, with prices there edging higher last week to $253 a tonne at Black Sea ports for 12.5% protein grain, Ikar said, and some exporters quoting December prices of $258-260 a tonne.
The country's late harvest has been affected by rains.
Wheat for December closed down 0.6% at $6.78 ½ a bushel in Chicago, the first negative close in six sessions.
In Kansas, the December lot added 1.1% to $7.39 ½ a bushel, a three-month closing high.
In Europe, Paris wheat for November eased 0.1% to E193.25 a tonne, but London wheat for November added 1.0% to £156.75 a tonne, getting a lift from the reopening of the Ensus bioethanol plant.