What are the disadvantages of using a small leverage?
The major drawback to borrowing to invest (i.e. using leverage) is that your return on investment must be high enough to overcome the cost of finance. The average return on the S&P 500 is about 9.8% (from CNBC) a typical unsecured personal loan will have an interest rate of around 18-36% APR (from NerdWallet). This means that on average you will be paying more interest than you are receiving in returns so are losing money on the margin investment. Sometimes the S&P falls and over those periods you would be paying out interest having lost money so will have a negative return! You may have better credit and so be able to get a lower rate but I don't know your loan terms currently. Secured loans, such as remortgaging your house, will have lower costs but come with more life changing risks. The above assumes that you are getting financing by directly borrowing money, however, it is also possible to trade on margin. This is where you post a proportion of the value that you wish to trade with as collateral against a loan to buy the security. This form of finance is normally used by day traders and other short term holders of stocks. Although the financing costs here are low (I am not charged an interest rate on intraday margin trading) there are very high costs if you exceed the term of the loan. An example is that I am charged a fee if I hold a position overnight and my profits and losses are crystallised at that time. If I am in a losing position at that time the crystallisation process and fee can result in not having enough margin to recover the position and the loss of a potentially profit making position. Additionally if the amount of collateral cash (margin) posted is insufficient to cover the expected losses as calculated by your broker they will initiate a margin call asking for more collateral money. If you do not (or cannot) post this extra margin your losing position will be cashed out and you will take as a loss the total loss at that time. Since the market can change very rapidly, such as in a flash crash, this can result in your losing more money than you had in the first place. As this is essentially a loan you can be bankrupted by this. Overall using leverage to invest magnifies your potential profits but it also magnifies your potential losses. In many cases this magnification could be sufficient to lose you more money than you had originally invested. In addition to magnification you need to consider the cost of finance and that your return over the course of the loan needs to be higher than your cost of finance as well as inflation and other opportunity costs of capital. The S&P 500 is a relatively low volatility market in general so is unlikely to return losses in any given period that will mean that leverage of 1.25 times will take you into losses beyond your own capital investment but it is not impossible. The low level of risk automatically means that your returns are lower and so your cost of capital is likely to be a large proportion of your returns and your returns may not completely cover the cost of capital even when you are making money. The key thing if you are going to trade or invest on leverage is to understand the terms and costs of your leverage and discount them from any returns that you receive before declaring to yourself that you are profitable. It is even more important than usual to know how your positions are doing and whether you are covering your cost of capital when using leverage. It is also very important to know the terms of your leverage in detail, especially what will happen when and if your credit runs out for whatever reason be it the end of the financing period (the length of the loan) or your leverage ratio gets too high. You should also be aware of the costs of closing out the loan early should you need to do so and how to factor that into your investing decisions.
I use over half my buying power of my portfolio for options, and I'm not a fan of any of the strategies listed above either (I stay away from negative theta trades for the most part), but I just listed them to point out that saying the reason someone wouldn't enter a short position is for fear of infinite losses is asinine. It's easy enough to make any trade risk defined if that is something the trader cares about. The main advantage of commodities to a largely stock and bond portfolio is diversification and the main disadvantages are investment complexity and low long-term returns. Let's start with the advantage.  Major commodities indices and the single commodities tend to be uncorrelated to stocks and bonds and will in general be diversifying especially over short periods.  This relationship can be complex though as Supply can be even more complicated (think weather) so diversification may or may not work in your favor over long periods. However, trading in commodities can be very complex and expensive.  Futures need to be rolled forward to keep an investment going.  You really, really don't want to accidentally take delivery of 40000 pounds of cattle.  Also, you need to properly take into account roll premiums (carry) when choosing the closing date for a future.  This can be made easier by using commodities index ETFs but they can also have issues with rolling and generally have higher fees than stock index ETFs. Most importantly, it is worth understanding that the long-term return from commodities should be by definition (roughly) the inflation rate.  With stocks and bonds you expect to make more than inflation over the long term.  This is why many large institutions talk about commodities in their portfolio they often actually mean either short term tactical/algorithmic trading or long term investments in stocks closely tied to commodities production or processing. The two disadvantages above are why commodities are not recommended for most individual investors. This isn't totally wrong- there are hedge funds that are long 150% of AUM and short 50%. However, Rentech has said that holding a position for 8 seconds is long for them, so that's not what they're doing. I'd assume the 4X leverage most just refers to option positions that have delta 4 on average. They also may be borrowing money, which they can probably do extremely cheaply since they have a 35 year track record showing they're essentially risk-free. Not really my field but this is how I see the impact   Disadvantages for banks : not being able to chose where they park assets/cash they have been trusted with which mean lower income from investing those  disadvantage for banks shareholders : less earnings   disadvantage for the economy : harder criteria to lend, lower loan growth   advantage for the economy : (theoretically) less risks of liquidity crunch and financial crisis I think George's answer explains fairly well why the brokerages don't allow this - it's not an exchange rule, it's just that the brokerage has to have the shares to lend, and normally those shares come from people's margin, which is impossible on a non-marginable stock. To address the question of what the alternatives are, on popular stocks like SIRI, a deep In-The-Money put is a fairly accurate emulation of an actual short interest.  If you look at the options on SIRI you will see that a $3 (or higher) put has a delta of -$1, which is the same delta as an actual short share. You also don't have to worry about problems like margin calls when buying options.  The only thing you have to worry about is the expiration date, which isn't generally a major issue if you're buying in-the-money options... unless you're very wrong about the direction of the stock, in which case you could lose everything, but that's always a risk with penny stocks no matter how you trade them. At least with a put option, the maximum amount you can lose is whatever you spent on the contract.  With a short sale, a bull rush on the stock could potentially wipe out your entire margin.  That's why, when betting on downward motion in a microcap or penny stock, I actually prefer to use options.  Just be aware that option contracts can generally only move in increments of $0.05, and that your brokerage will probably impose a bid-ask spread of up to $0.10, so the share price has to move down at least 10 cents (or 10% on a roughly $1 stock like SIRI) for you to just break even; definitely don't attempt to use this as a day-trading tool and go for longer expirations if you can. Leverage is when you borrow in order to invest. Mind you, most people aren't going to just give you money to gamble on the stock market completely unsecured; rather, you deposit (say) $10,000 and buy a stock... and then you have $10k in assets which you can borrow against, so you can buy another $10,000 of that stock. Now if the stock goes up you'll make twice the gain (2x leverage). However, if it goes down, you'll lose twice as much as well. If the value of your stock falls, your line of credit will be reduced as well; in this case, since you used all your credit and are now over your limit, your broker will issue a margin call (they will demand a deposit of additional funds, or they will sell some of your stock at their discretion). This protects you from owing more than you invested, but it's still sometimes possible (for instance, if a company spontaneously goes bankrupt and becomes worthless, and your stock becomes worthless). There are also things like leveraged index funds and commodity funds which aim to return some multiple of the market's earnings. These are designed for intraday trading, though, and usually end up underperforming significantly over the long term. [edit] Mose people who accept borrowed funds should generally accept real cash as well. However, if you're trying to short sell, i.e. borrow shares and sell them (in the hopes you can get them back cheaper later after the stock falls) you will need a margin line of credit to do so as well. [edit 2] clarified margin calls Yes, 6% is a waste of money, because some other brokers such as IB offer margin rates below 2%.   Also, to borrow money for even less than any broker's margin interest rate, one can do an EFP transaction.   This involves simultaneously shorting a stock and buying the SSF for the same stock.   When the futures contract expires, you take delivery of the underlying stock to automatically close out your short position.  Until then, you've effectively borrowed cash for the cost of borrowing the stock, which is typically less than 0.5% interest for widely traded ones.  You also pay for the slight difference in price between the stock and the future, which is typically equivalent to another 0.5% interest or less.  The total often comes to less than 1% interest. The only risk with this transaction is that the stock could become hard to borrow at some point, so then you would have to pay higher interest on it temporarily or maybe even have to close out your short early.  But it is extremely rare for large, high-volume stocks to become hard-to-borrow.  The borrowing cost of SPY has spiked above 5% on only a handful of days in the last decade. Yes, more leverage increases the variance of your individual portfolio (variance of your personal net worth). The simple way to think about it is that if you only own only 50% of your risky assets, then you can own twice as many risky assets. That means they will move around twice as much (in absolute terms). Expected returns and risk (if risk is variance) both go up. If you lend rather than borrow, then you might have only half your net worth in risky assets, and then your expected returns and variation in returns will go down. Note, the practice of using leverage differs from portfolio theory in a couple important ways. You can only lose your 7%. The idea that a certain security is more volatile than others in your portfolio does not mean that you can lose more than the value of the investment. The one exception is that a short position has unlimited downside, but i dont think there are any straight short mutual funds. Another disadvantage is the inability to value commodities in an accounting sense. In contrast with stocks, bonds and real estate, commodities don't generate cash flows and so any valuation methodology is by definition speculative. But as rhaskett notes, there are diversification advantages. The returns for gold, for instance, tend to exhibit low/negative correlation with the performance of stocks. The question is whether the diversification advantage, which is the primary reason to hold commodities in a multi-asset class portfolio through time, overcomes the disadvantages? The answer... maybe. That's not 100% correct, as some leveraged vehicles choose to re-balance on a monthly basis making them less risky (but still risky).  If I'm not mistaken the former oil ETN 'DXO' was a monthly re-balance before it was shut down by the 'man' Monthly leveraged vehicles will still suffer slippage, not saying they won't.  But instead of re-balancing 250 times per year, they do it 12 times.   In my book less iterations equals less decay. Basically you'll bleed, just not as much.  I'd only swing trade something like this in a retirement account where I'd be prohibited from trading options. Seems like you can get higher leverage with less risk trading options, plus if you traded LEAPS, you could choose to re-balance only once per year. Well, I didn't know those existed. Author might not either.  I'm also not aware of the trading requirements in Europe. Could be different than US.  In any event, I think most who are concerned are (1) doomsayers who've predicted 30 of the last 1 recessions, (2) don't understand the point of leverage and are irrationally scared of it, or (3) understand leverage can be good but think this will be used in a bad way. The main advantage and disadvantage I can see in a scenario like this are - how savvy and good an investor are you? It's a good way to create below-market average returns if you're not that good at investing and returns way above market average if you are... Your original example is a little confusing because just shorting for 1k and buying for 1k is 100% leveraged or an infinitive leverage ratio. (and not allowed) Brokerage houses would require you to invest some capital in the trade.  One example might be requiring you to hold $100 in the brokerage.  This is where the 10:1 ratio comes from. (1000/10) Thus a return of 4.5% on the 1000k bond and no movement on the short position would net you $45 and voila a 45% return on your $100 investment. A 40 to 1 leverage ratio would mean that you would only have to invest $25 to make this trade.  Something that no individual investor are allowed to do, but for some reason some financial firms have been able to. "Leverage means you can make more investments with the same amount of money.  In the case of rental properties, it means you can own more properties and generate more rents.  You exchange a higher cost of doing business (higher interest fees) and a higher risk of total failure, for a larger number of rents and thus higher potential earnings. As with any investment advice, whenever someone tells you ""Do X and you are guaranteed to make more money"", unless you are a printer of money that is not entirely true. In this case, taking more leverage exposes you to more risk, while giving you more potential gain.  That risk is not only on the selling front; in fact, for most small property owners, the risk is primarily that you will have periods of time of higher expense or lower income.  These can come in several ways: If you weather these and similar problems, then you will stand to make more money using higher leverage, assuming you make more money from each property than your additional interest costs.  As long as you're making any money on your properties this is likely (as interest rates are very low right now), but making any money at all (above and beyond the sale value) may be challenging early on.   These sorts of risks are magnified for your first few years, until you've built up a significant reserve to keep your business afloat in downturns.  And of course, any money in a reserve is money you're not leveraging for new property acquisition - the very same trade-off.  And while you may be able to sell one or more properties if you did end up in a temporarily bad situation, you also may run into 2008 again and be unable to do so."