Evidence for/against negative correlation between commodity futures, stocks
"The correlation I heard most about in economics/finance was that stock prices and bond yields were negatively correlated; as the stock market does better, bond yields fall (company's doing well as evidenced by stocks, so it's a good credit risk, so YTM of its bonds on the market goes down). The correlation, if any, between the stock and futures market should be visible in the actual price histories. Index prices may be useful, but what's more likely is that various future prices have correlation with various companies' stocks. Where the future reflects the price of a raw material that is a significant cost of goods sold for a company, you'll see these two move inversely to each other in the short term. I think that if there is a causative relationship here, its that futures prices influence stock prices, not the other way around. The futures market generally represents the cost side of a consumer goods producer's bottom line. The stock market represents its profits. As futures go up, profit expectations go down, putting pressure on stock prices. Industries that deal in services, or in other types of goods, can still be affected because a rise in the cost of something consumers need will cause them to spend less on other things which affects margins in those other areas. So, in the short and medium term, when the futures market goes up the stock market sees a dip, and vice versa.  However, companies adapt; they can put upward pressure on prices for their goods to restore their desired margins, usually by slowly increasing them to prevent sticker shock (though elasticity of demand plays a part; the more we need something no matter what it costs, the faster prices can increase). To maintain costs, they can make things cheaper using less expensive materials (more plastic, less steel). They can restructure production processes (translated: move factories offshore, or at least to ""right-to-work"" states with less union strength) to save costs elsewhere. All of these reduce costs and thus increase profits, but take time to implement. Many of these things reduce direct costs, reducing demand for the commodity and causing the futures prices to go back down. So, over the long term, these differences even out, and it's down to the things that affect the entire market (inflation, consumer/investor confidence, monetary policy)."
"They're certainly a factor.  Am I misunderstanding your comment?  The only way it seems to parse is if you're saying that a person who is ""earning 15K a year, no healthcare, little education, and living in poor neighborhoods ridden with theft and violence "" is not overweight, presumably for reasons at least related to the factors you gave as reasons.  But I don't see any obvious negative correlation between those things and obesity, which you appeared to be trying to claim." Nobody tracks a single company's net assets on a daily basis, and stock prices are almost never derived directly from their assets (otherwise there would be no concept of 'growth stocks').  Stocks trade on the presumed current value of future positive cash flow, not on the value of their assets alone. Funds are totally different.  They own nothing but stocks and are valued on the basis on the value of those stocks.  (Commodity funds and closed funds muddy the picture somewhat, but basically a fund's only business is owning very liquid assets, not using their assets to produce wealth the way companies do.) A fund has no meaning other than the direct value of its assets.   Even companies which own and exploit large assets, like resource companies, are far more complicated than funds: e.g. gold mining or oil extracting companies derive most of their value from their physical holdings, but those holdings value depends on the moving price and assumed future price of the commodity and also on the operations (efficiency of extraction etc.) Still different from a fund which only owns very liquid assets. "The main difference between a bull market and a bear market is due the ""the leverage effect"". http://www.princeton.edu/~yacine/leverage.pdf The leverage effect refers to the observed tendency of an asset’s   volatility to be negatively correlated with the asset’s returns.   Typically, rising asset prices are accompanied by declining   volatility, and vice versa. The term “leverage” refers to one possible   economic interpretation of this phenomenon, developed in Black (1976)   and Christie (1982): as asset prices decline, companies become   mechanically more leveraged since the relative value of their debt   rises relative to that of their equity. As a result, it is natural to   expect that their stock becomes riskier, hence more volatile. More volatile assets in a bear market are not such good investments as less volatile assets in a bull market." "Index funds may invest either in index components directly or in other instruments (like ETFs, index options, futures, etc.) which are highly correlated with the index. The specific fund prospectus or description on any decent financial site should contain these details.  Index funds are not actively managed, but that does not mean they aren't managed at all - if index changes and the fund includes specific stock, they would adjust the fund content. Of course, the downside of it is that selling off large amounts of certain stock (on its low point, since it's being excluded presumably because of its decline) and buying large amount of different stock (on its raising point) may have certain costs, which would cause the fund lag behind the index. Usually the difference is not overly large, but it exists.  Investing in the index contents directly involves more transactions - which the fund distributes between members, so it doesn't usually buy individually for each member but manages the portfolio in big chunks, which saves costs. Of course, the downside is that it can lag behind the index if it's volatile. Also, in order to buy specific shares, you will have to shell out for a number of whole share prices - which for a big index may be a substantial sum and won't allow you much flexibility (like ""I want to withdraw half of my investment in S&P 500"") since you can't usually own 1/10 of a share. With index funds, the entry price is usually quite low and increments in which you can add or withdraw funds are low too." My view is that hedge funds and high-frequency traders tend to create this correlation because they're making directional bets on individual stocks, grouped as a whole, and then share these ideas with so many other funds (who, in turn, do the same thing).  I think Beta and inflated share prices are related to this effect, but are not the cause of this effect. well well, good question, worth a discussion, the more filters you add to your strategy (volatility in this case), the lower its predictive power. i mean, one could further filter it by day of the week, whether prices are above or below a 200 day moving average...etc. "If you're simply a futures speculator, then yes, it does seem like gambling. If you're a farmer producing a few thousand bushels of wheat, futures can be a mechanism for you to hedge against certain kinds of market risk. Same if you're running a heating oil company, etc. I just read somewhere that the bad spring weather in South Dakota has prevented farmers from getting corn planted -- nothing is in the ground yet. This is ""objective data"" from which you might infer that this year's corn harvest could be late and/or smaller than normal. So maybe if you're a buyer for General Mills, you use corn futures to control your costs. In this case you'd have some idea based on experience what to expect for the price of corn, what your production line requires for input, how much you can charge for finished product, etc. These all factor in to the price you'd be willing to pay for corn futures." "Of course, which is why you need to have a scoring function / utility function for the ""filters"", i.e. Are you going to value it by rate of accuracy hor by a metric where wins = +2, losses = -1, such that it uses a criteria like that to decide whether or not a filter adds value, (some even use a compound effect i.e. wins = 2+e^(1+w) where w is the consecutive wins).  A metric like the above would capture the trade off between predictive power and profit. Also some traders watch their Max DD very carefully so they may be very risk averse."