According the BBC, half of the world's heroin supply is missing. There seem to be two main theories as to why this is: either some countries are drastically under-reporting their rate of heroin use (Russia? China?), or someone somewhere has a big fucking warehouse stuffed full of pure heroin.
I propose a third possibility: in the same way that the people in charge of big trading companies seem to be able to magically make billions of dollars disappear, the people in charge of big heroin operations are magically making thousands of kilos of heroin disappear. Stockpiling it all in one place makes no sense -- too much risk, not much upside. But spreading it around makes more sense -- no one would have enough to hedge against the global market, but everyone involved would have enough to insure continuity of supply in case of, say, a major US offensive against opium growers in Afghanistan.
So get your money out of the heroin market now! Invest in safer commodities like LSD and ecstasy -- much lower production and transportation costs, plus much, much easier to stockpile (a suitcase instead of a warehouse, say). And in this new age of tight credit, it's the intangible costs that'll bite you in the ass.