How does a portfolio of long stocks and short futures generate profits
"I know some derivative markets work like this, so maybe similar with futures.  A futures contract commits two parties to a buy/sell of the underlying securities, but with a futures contract you also create leverage because generally the margin you post on your futures contract is not sufficient to pay for the collateral in the underlying contract. The person buying the future is essentially ""borrowing"" money while the person selling the future is essentially ""lending"" money. The future you enter into is generally a short term contract, so a perfectly hedged lender of funds should expect to receive something that approaches the fed funds rate in the US. Today that would be essentially nothing."
Well, arbitrage is a simple mean reversion strategy which states that any two similar commodity with some price difference (usually not much)  will converge. So either you can bet on difference in prices in different exchanges or also you can bet on difference in futures value.  For example if current price of stock is 14$ and if futures price is 10$.  Then you can buy one futures contract and short one stock at the market price. This would lock in a profit of 4$ per share. News-driven investors tend to be very short-term focussed investors. They often trade by using index futures (on the S&P 500 index for instance). There are several ways that the issuers profit from CFDs. If the broker has trades on both sides (buy and sell) they can net the volumes off against each other and profit off the spread whilst using the posted margins to cover p&l from both sides. Because settlement for most securities is not on the same day that the order is placed they can also buy the security with no intention of taking delivery and simply sell it off at the end of day to pass delivery on to someone else. Here again they profit from the spread and that their volumes give them really low commissions so their costs are much lower than the value of the spread. If they have to do this rather than netting the position out the spreads will be wider.  Sometimes that may be forced to buy the security outright but that is rare and the spreads will be even wider so that they can make a decent profit. "Largely, because stock markets are efficient markets, at least mostly if not entirely; while the efficient market hypothesis is not necessarily 100% correct, for the majority of traders it's unlikely that you could (on the long term) find significant market inefficiencies with the tools available to an individual of normal wealth (say, < $500k). That's what frequent trading intends to do: find market inefficiencies.  If the market is efficient, then a stock is priced exactly at what it should be worth, based on risk and future returns.  If it is inefficient, then you can make more money trading on that inefficiency versus simply holding it long.  But in stating that a stock is inefficient, you are stating that you know something the rest of the market doesn't - or some condition is different for you than the other million or so people in the market.  That's including a lot of folks who do this for a living, and have very expensive modelling software (and hardware to run it on).  I like to think that I'm smarter than the far majority of people, but I'm probably not the smartest guy in the room, and I certainly don't have that kind of equipment - especially with high frequency trading nowadays. As such, it's certainly possible to make a bit of money as a trader versus as a long-term investor, but on the whole it's similar to playing poker for a living.  If you're smarter than most of the people in the room, you might be able to make a bit of money, but the overhead - in the case of poker, the money the house charges for the game, in the case of stocks, the exchange fees and broker commissions - means that it's a losing game for the group as a whole, and not very many people can actually make money.  Add to that the computer-based trading - so imagine a poker game where four of the eight players are computer models that are really good (and actively maintained by very smart traders) and you can see where it gets to be very difficult to trade at a profit (versus long term investments, which take advantage of the growth in value in the company). Finally, the risk because of leverage and option trading (which is necessary to really take advantage of inefficiencies) makes it not only hard to make a profit, but easy to lose everything.  Again to the poker analogy, the guys I've known playing poker for a living do it by playing 10-20 games at once - because one game isn't efficient enough, you wouldn't make enough money.  In poker, you can do that fairly safely, especially in limit games; but in the market, if you're leveraging your money you risk losing a lot.  Every action you take to make it ""safer"" removes some of your profit." Highest possible is meaningless.  Ex: Use 17x Leverage on E-mini S&P 500 Futures, perfectly long before an uptick and short before a downtick every minute. Goes to the moon in a day of 1,440 minutes.  You are supposed to use a Buy-and-Hold SPY, with leverage that makes the Standard Deviation of SPY same as your Portfolio/Algorithm, as benchmark. They will make money from brokerage as usual and also from the interest they charge you for lending you the money for you to buy your shares on margin. In other words you will be paying interest on the $30,000 you borrowed from your broker. Also, as per Chris's comment, if you are shorting securities through your margin account, your broker would charge you a fee for lending you the securities to short. Correct, long/short strategies should have zero beta with the stock market. But this is intentional, and investors in true *hedged* funds seek this *portable alpha* as a complement to their long-only sleeve in the portfolio.  My question is: if for example, you are long low P/E stocks, and a short high P/E stocks what *creates* the alpha? Your portfolio should have zero beta. I believe in the long-run this long/short P/E strategy [generates ~300 basis points of return per year (un-levered)](http://mba.tuck.dartmouth.edu/pages/faculty/ken.french/data_library.html).  Is not reasonable to assume if returns from long only investing is driven by beta (and investors use 6% to 12% discount rates in their valuation models), then an an un-levered long/short strategy should always under-perform a long-only strategy in the long-run. The purpose of long/short strategies is not to beat long-only investing, it is to create [portable alpha](https://en.wikipedia.org/wiki/Portable_alpha).  In fact, at a high level of abstraction, the *average* long/short strategy should not earn a return greater than the risk free rate in the long-run because the strategy has zero beta. "You're talking about modern portfolio theory. The wiki article goes into the math. Here's the gist: Modern portfolio theory (MPT) is a theory of finance that attempts to maximize portfolio expected return for a given amount of portfolio risk, or equivalently minimize risk for a given level of expected return, by carefully choosing the proportions of various assets. At the most basic level, you either a) pick a level of risk (standard deviation of your whole portfolio) that you're ok with and find the maximum return you can achieve while not exceeding your risk level, or b) pick a level of expected return that you want and minimize risk (again, the standard deviation of your portfolio). You don't maximize both moments at once. The techniques behind actually solving them in all but the most trivial cases (portfolios of two or three assets are trivial cases) are basically quadratic programming because to be realistic, you might have a portfolio that a) doesn't allow short sales for all instruments, and/or b) has some securities that can't be held in fractional amounts (like ETF's or bonds). Then there isn't a closed form solution and you need computational techniques like mixed integer quadratic programming Plenty of firms and people use these techniques, even in their most basic form. Also your terms are a bit strange: It has correlation table p11, p12, ... pij, pnn for i and j running from 1 to n This is usually called the covariance matrix. I want to maximize 2 variables. Namely the expected return and the additive inverse of the standard deviation of the mixed investments. Like I said above you don't maximize two moments (return and inverse of risk). I realize that you're trying to minimize risk by maximizing ""negative risk"" so to speak but since risk and return are inherently a tradeoff you can't achieve the best of both worlds. Maybe I should point out that although the above sounds nice, and, theoretically, it's sound, as one of the comments points out, it's harder to apply in practice. For example it's easy to calculate a covariance matrix between the returns of two or more assets, but in the simplest case of modern portfolio theory, the assumption is that those covariances don't change over your time horizon. Also coming up with a realistic measure of your level of risk can be tricky. For example you may be ok with a standard deviation of 20% in the positive direction but only be ok with a standard deviation of 5% in the negative direction. Basically in your head, the distribution of returns you want probably has negative skewness:  because on the whole you want more positive returns than negative returns. Like I said this can get complicated because then you start minimizing other forms of risk like value at risk, for example, and then modern portfolio theory doesn't necessarily give you closed form solutions anymore. Any actively managed fund that applies this in practice (since obviously a completely passive fund will just replicate the index and not try to minimize risk or anything like that) will probably be using something like the above, or at least something that's more complicated than the basic undergrad portfolio optimization that I talked about above. We'll quickly get beyond what I know at this rate, so maybe I should stop there." The Explanation is correct. The Traders buys the 1st call and profits linearly form 40$ onwards. At at 45 the short call kick in and neutralizes any further profit on the first call. The stock market's principal justification is matching investors with investment opportunities.  That's only reasonably feasible with long-term investments.  High frequency traders are not interested in investments, they are interested in buying cheap and selling expensive.  Holding reasonably robust shares for longer binds their capital which is one reason the faster-paced business of dealing with options is popular instead.  So their main manner of operation is leeching off actually occuring investments by letting the investors pay more than the recipients of the investments receive. By now, the majority of stock market business is indirect and tries guessing where the money goes rather than where the business goes. For one thing, this leads to the stock market's evaluations being largely inflated over the actual underlying committed deals happening.  And as the commitment to an investment becomes rare, the market becomes more volatile and instable: it's money running in circles. Fast trading is about running in front of where the money goes, anticipating the market.  But if there is no actual market to anticipate, only people running before the imagination of other people running before money, the net payout converges to zero as the ratio of serious actual investments in tangible targets declines. By and large, high frequency trading converges to a Ponzi scheme, and you try being among the winners of such a scheme.  But there are a whole lot of people competing here, and essentially the net payoff is close to zero due to the large volumes in circulation as opposed to what ends up in actual tangible investments. It's a completely different game with different rules riding on the original idea of a stock market.  So you have to figure out what your money should be doing according to your plans. I was referring to insider information as a seperate means of profiting. So I assumed:  1. Fundamental analysis/picking the direction 2. Insider information 3. Gaming the market (illiquid markets)  If this is true. What makes a good market maker? Stoploss/takeprofit management and hope there are enough players in it *not* to win it (i.e. hedge positions) to take profit from?  Sounds very luck base or is there something im missing?  Thanks In the short term the market is a popularity contest In the short run which in value investing time can extend even to many years, an equity is subject to the vicissitudes of the whims by every scale of panic and elation. This can be seen by examining the daily chart of any large cap equity in the US.  Even such large holdings can be affected by any set of fear and greed in the market and in the subset of traders trading the equity. Quantitatively, this statement means that equities experience high variance in the short rurn. in the long term [the stock market] is a weighing machine In the long run which in value investing time can extend to even multiple decades, an equity is more or less subject only to the variance of the underlying value. This can be seen by examining the annual chart of even the smallest cap equities over decades.  An equity over such time periods is almost exclusively affected by its changes in value. Quantitatively, this statement means that equities experience low variance in the long run. "Being ""long"" - expecting the price to go up to make a profit - is a two step process:  1) buy 2) sell Being ""short"" - expecting the price to go down to make a profit - is a 5 step process:  1) borrow someone else's asset 2) sell their asset on the open market to somebody else a third party 3) pocket the proceeds of the sell for your own account 4) buy an identical asset for a cheaper price 5) return this identical asset to the person that let you borrow their asset if this is successful you keep the difference between 3) and 4)" As far as i understand the big companies on the stock markets have automated processes that sit VERY close to the stock feeds and continually processes these with the intention of identifying an opportunity to take multiple small lots and buy/sell them as a big lot or vice/versa and do this before a buy or sell completes, thus enabling them to intercept the trade and make a small profit on the delta. With enough of these small gains on enough shares they make big profits and with near zero chance of losing. This has been made clearly many times in this thread and others, and by myself. I refuse to go around in circles so I will not repeat myself after this: long term investors need to be able to liquidate their assets. Since long term investors by definition trade infrequently, short term speculators are NECESSARY to perform this function. Your argument at times has been that you don't need ULTRA short term speculators, and mine is that the ULTRA sort term speculators have not been shown to do anything negative to long term investors so banning them is reactionary. Short term speculators DO make money out of long term investors and that is by design - they are the very reason markets exist; otherwise people would stick to direct investment!