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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.