I guess it must be. No different than hoarding a stock, I suppose. Or is it more like price-manipulation? U.S. Weighs Inquiry Into Big Banks’ Storage of Commodities. Cornering markets? Soros got very rich doing this. So did the Hunt family, for a while.
Here's the other side of the story (h/t reader): Aluminum, Goldman, The Times, And BS
And, hey - what about those Saudis warehousing all that oil in the ground until prices rise?