The evidence presented in that doesn't support the argument being made. At best it could be taken both ways, at worst the author is clearly taking what they want to see from the evidence, and ignoring the inconvenient parts of it.
I'm a bit of a layman in terms of the markets, but when discussing the impact of the futures market, why would someone use graphs showing the spot price vs the level of investment in the futures market (exhibit C) and then try to directly correlate the two, demonstrate there's no correlation, then use this as evidence to refute the hypothesis regarding the impact of the futures market if they weren't deliberately setting out to mislead?
As I understand it, in general terms the futures market wouldn't be expected to have much impact on the immediate spot price of a commodity, if there were an effect on the spot price it would be on the price of the commodity at the point when those futures trades were set to mature, so for arguments sake 6 months to a year after the initial investment. In order to view whether there is a correlation or not I'd think that it would therefore be necessary to do the correlation calculations on the value of futures vs the spot price 6 months to 1 year later (or whatever the average length of the futures trade was).
If you look at the figures this way, there seems to be a fairly clear correlation between the level of investment / gambling, and the level of the commodity price swings a year later (over the last few years when investment levels have been highest anyway.). I don't have the software to perform such analysis (and couldn't remember how to do it anyway), but maybe YMU would fancy doing the honours to see if such a correlation does exist - although I'd think the actual data period if we only took the last few years would be too short to make it possible to demonstrate a correlation to a high level of certainty.
The author makes some other blatantly misleading comments that aren't backed up by the data they provide, including:
Exhibit A - commodity price rise vs levels of investment, the author argues that the increase in the value of investment is caused by the increase in the commodity value... according to the graph supplied, the commodity price has increased by roughly 400% since 2000, while the value of the 'long commodity assets' have increased by over 5000%.
That argument is obviously and demonstrably false then, with under 10% of the increase in the size of the market being down to the commodity price rise, and over 90% being down to an actual influx of new money into the marketplace.
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The author tries to show that the volume of trade is too small relative to the overall size of the market to influence prices significantly, but negates to mention the simple fact that these markets operate with small percentages of surplus production, and that swings in the supply or demand of these products of only a few percent are capable of leading to dramatic increases or decreases in the price of those products of 10x or more the actual swing in production / consumption levels. 2010 positions of 7% of the global wheat market, or 6% of the global gas market then are more than big enough to drastically impact on the price of those commodities, particularly if there are other factors also in play at the time.
For example, the supply interuptions from 1972-74 due to reductions in output from the middle east amounted to a 7% reduction in global output, but led to a 400% spike in the oil price, and for comparison purposes, the global spare oil production capacity used to attempt to smooth out the oil price is approx 1% of production. Futures trade running at anything above the level of the spare capacity blatantly must have the ability to dramatically influence the oil price. According to this article (exhibit G) it's currently running at 4% of world production value, and therefore fully capable of significantly influencing the price level.
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basically this seems to be disingenuous bullshit served up by someone with a vast personal and professional interest in maintaining the status quo - I don't believe for a second that the author didn't know exactly what they were doing by presenting the data in the way they did.