Can I profit from anticipating a drop in value?
To expand on the comment made by @NateEldredge, you're looking to take a short position.  A short position essentially functions as follows:  Here's the rub: you have unlimited loss potential.  Maybe you borrow a share and sell it at $10.  Maybe in a month you still haven't closed the position and now the share is trading at $1,000.  The share lender comes calling for their share and you have to close the position at $1,000 for a loss of $990.  Now what if it was $1,000,000 per share, etc. To avoid this unlimited loss risk, you can instead buy a put option contract.  In this situation you buy a contract that will expire at some point in the future for the right to sell a share of stock for $x.  You get to put that share on to someone else. If the underlying stock price were to instead rise above the put's exercise price, the put will expire worthless — but your loss is limited to the premium paid to acquire the put option contract. There are all sorts of advanced options trades sometimes including taking a short or long position in a security.  It's generally not advisable to undertake these sorts of trades until you're very comfortable with the mechanics of the contracts.  It's definitely not advisable to take an unhedged short position, either by borrowing someone else's share(s) to sell or selling an option (when you sell the option you take the risk), because of the unlimited loss potential described above. Purchasing an option to sell the stock is probably the safest bet. This gives you reasonable leverage, and your risk is limited to the cost of the option. Say the stock currently sells for $100 per share. You think it will drop to $80 per share in the next two weeks and the market thinks the price will be stable. Now, consider an option to sell one share of that stock for $95 any time within the next two weeks. The market would consider that option nearly worthless, since in all likelihood, you would lose out by exercising it (since you could just sell the share on the market for a price expected to be higher than that). You might be able to acquire that option for $5. Now, say you're right and within two weeks, the price drops to $80. Now you can purchase a share for $80, exercise the option to sell it for $95, and pocket $15. That would make you a $10 profit on a $5 investment. If you're wrong, you just let the option lapse and are out $5. No problem. In reality, you would buy a number of such options. And you wouldn't actually buy a share and exercise the option, you would just sell the option back to its issuer for $15. "To summarize, there are three basic ways: (3) is the truly dangerous one. If there is a lot of short interest in a stock, but for some reason the stock goes up, suddenly a lot of people will be scrambling to buy that stock to cover their short position -- which will drive the price up even further, making the problem worse.  Pretty soon, a bunch of smart rich guys will be poor guys who are suddenly very aware that they aren't as smart as they thought they were.  Eight years ago, such a ""short squeeze"", as it's called, made the price of VW quadruple in two days.  You could hear the Heinies howl from Hamburg to Haldenwanger. There are ways to protect yourself, of course.  You can go short but also buy a call at a much higher price, thereby limiting your exposure, a strategy called a ""straddle"", but you also reduce your profit if you guessed right. It comes down to, as it always does, do you want to eat well, or to sleep well?"
It seems to be that your main point is this: No matter what, my chances cannot be worse than random and if my trading system has an edge that is greater than the percentage of the transaction that is transaction cost, then I am probabilistically likely to make a profit? In general, yes, that is true, but... Consider this very bad strategy: Buy one share of stock and sell it one minute later, and repeat this every minute of the day. Obviously you would bleed your account dry with fees. However, even this horrible strategy still meets your criteria because: if this bad strategy had an edge beyond the transaction fees you would likely still make a profit. In other words, your conclusion reduces to an uninteresting statement: If there were no transactions fees, then if your trading system has an edge then you will likely make a profit. Sorry to be the bearer of bad news, but IMHO, that statement, and others made in the question are just obvious things stated in convoluted ways. I don't want to discourage you from thinking about these things though. I personally really enjoy these type of thought experiments. I just feel you missed the mark on this one... The satisfaction from gains packs less of an emotional impact than the fear of loss. It's very difficult for many people to overcome this fear, so when prices begin to fall, many investors sell to minimize their potential loss. This causes a further drop, which can lead to more selling as other investors reach their emotional threshold for loss. This emotion-based selling keeps the market inefficient in the short term. If there aren't enough value investors waiting to scoop up the stock at the new discount, it can stay undervalued for a long time. "No. Some grocery stores may discount specific products based on inventory to drive sales using ""loss leaders"" where the product is intentionally priced as a loss for the business. While commodity futures may impact some prices, I'm not sure one can easily extract the changes solely due to futures shifts." Yes, one such strategy is dividend arbitrage using stock and in the money options. You have to find out which option is the most mispriced before the ex-dividend date. "If the stock market dropped 30%-40% next month, providing you with a rare opportunity to buy stocks at a deep discount, wouldn't you want to have some of your assets in investments other than stocks? If you don't otherwise have piles of new cash to throw into the market when it significantly tanks, then having some of your portfolio invested elsewhere will enable you to back up the proverbial truck and load up on more stocks while they are on sale. I'm not advocating active market timing. Rather, the way that long-term investors capitalize on such opportunities is by choosing a portfolio asset allocation that includes some percentage of safer assets (e.g. cash, short term bonds, etc.), permitting the investor to rebalance the portfolio periodically back to target allocations (e.g. 80% stocks, 20% bonds.) When rebalancing would have you buy stocks, it's usually because they are on sale. Similarly, when rebalancing would have you sell stocks, it's usually because they are overpriced. So, don't consider ""safer investments"" strictly as a way to reduce your risk. Rather, they can give you the means to take advantage of market drops, rather than just riding it out when you are already 100% invested in stocks. I could say a lot more about diversification and risk reduction, but there are plenty of other great questions on the site that you can look through instead." I think the simple answer to your question is: Yes, when you sell, that drives down the price. But it's not like you sell, and THEN the price goes down. The price goes down when you sell. You get the lower price.  Others have discussed the mechanics of this, but I think the relevant point for your question is that when you offer shares for sale, buyers now have more choices of where to buy from. If without you, there were 10 people willing to sell for $100 and 10 people willing to buy for $100, then there will be 10 sales at $100. But if you now offer to sell, there are 11 people selling for $100 and 10 people buying for $100. The buyers have a choice, and for a seller to get them to pick him, he has to drop his price a little. In real life, the market is stable when one of those sellers drops his price enough that an 11th buyer decides that he now wants to buy at the lower price, or until one of the other 10 buyers decides that the price has gone too low and he's no longer interested in selling. If the next day you bought the stock back, you are now returning the market to where it was before you sold. Assuming that everything else in the market was unchanged, you would have to pay the same price to buy the stock back that you got when you sold it. Your net profit would be zero. Actually you'd have a loss because you'd have to pay the broker's commission on both transactions. Of course in real life the chances that everything else in the market is unchanged are very small. So if you're a typical small-fry kind of person like me, someone who might be buying and selling a few hundred or a few thousand dollars worth of a company that is worth hundreds of millions, other factors in the market will totally swamp the effect of your little transaction. So when you went to buy back the next day, you might find that the price had gone down, you can buy your shares back for less than you sold them, and pocket the difference. Or the price might have gone up and you take a loss. Trying to engage in arbitrage with the metal in nickels (which was actually worth more than a nickel already, last I checked) is cute but illegal, and would be more effective at an industrial scale anyway (I don't think you could make it cost-effective at an individual level). There are more effective inflation hedges than nickels and booze. Some of them even earn you interest. You could at least consider a more traditional commodities play - it's certainly a popular strategy these days. A lot of people shoot for gold, as it's a traditional hedge in a crisis, but there are concerns that particular market is overheated, so you might consider alternatives to that. Normal equities (i.e. the stock market) usually work out okay in an inflationary environment, and can earn you a return as they're doing so.... and it's not like commodities aren't volatile and subject to the whims of the world economy too. TIPs (inflation-indexed Treasury bonds) are another option with less risk, but also a weaker return (and still have interest rate risks involved, since those aren't directly tied to inflation either). No free lunch You cannot receive risk-free interest on more money than you actually put down. The construct you are proposing is called 'Carry Trade', and will yield you the interest-difference in exchange for assuming currency risk. Negative expectation In the long run one would expect the higher-yielding currency to devalue faster, at a rate that exactly negates the difference in interest. Net profit is therefore zero in the long run. Now factor in the premium that a (forex) broker charges, and now you may expect losses the size of which depends on the leverage chosen. If there was any way that this could reliably produce a profit even without friction (i.e. roll-over, transaction costs, spread), quants would have already arbitraged it away. Intransparancy Additionaly, in my experience true long-term roll-over costs in relation to interest are a lot harder to compute than, for example, the cost of a stock transaction. This makes the whole deal very intransparant. As to the idea of artificially constructing a USD/USD pair: I regret to tell you that such a construct is not possible. For further info, see this question on Carry Trade: Why does Currency Carry Trade work? "The technical term for it is ""timing the market"" and if you can pull it off correctly, you will do quite well. The problem is that it is almost impossible to consistently do well. If it were that easy there would be a lot of billionaires walking around. Even Wall street experts haven't been able to predict the market that well. This idea is almost universally considered a bad idea. Consider this: When has the stock dropped low enough that you are ""buying low"" and let's say you do buy low and it doubles in a month. When do you get out? What if you are wrong and it doubles again? Or if it drops 10% do you keep waiting? This strategy is rife with problems." In your own example of VW, it dropped from its peak price of $253 to $92. If you had invested $10,000 in VW in April 2015, by September of that year it would have gone down to $3,600. If you held on to your investment, you would now be getting back to $6,700 on that original $10,000 investment. Your own example demonstrates that it is possible to lose. I have a friend who put his fortune into a company called WorldCom (one of the examples D Stanley shared). He actually lost all of his retirement. Luckily he made some money back when the startup we both worked for was sold to a much larger company. Unsophisticated investors lose money all the time by investing in individual companies. Your best bet is to start searching this site for answers on how to invest your money so that you can see actual strategies that reduce your investment risk. Here's a starting point: Best way to start investing, for a young person just starting their career? If you want to better illustrate this principle to yourself, try this stock market simulation game. One possibility is to lock in gains by selling, where a selling price can attempt to be optimized by initiating a trailing stop loss order. You'll have to look at the pros and cons of that kind of order to see if it is right for you. Another possibility is to begin hedging with options contracts, if that security is optionable. Puts with the appropriate delta will cost over time against future gains in the stock's price, but will protect your wealth if the stock price falls from this high point. These possibilities depend on what your investment goals are. For instance, if you are buying no matter what price because you like the forward guidance of the company, then it changes your capital growth and preservation decisions. I am relative newbie in the financial market trading and as I understand it, the response from Victor is accurate in respect of trading CFD contracts. However, there is also the option to 'trade' through a financial spread betting platform which as its name suggests is purely a bet based upon the price of the underlying stock/asset. As such, I believe that your theory to short a stock just prior to its ex-dividend date may be worth investigating further... Apart from that, it's worthwhile mentioning that financial spread betting is officially recognised by HMRC as gambling and therefore not currently [2015/16] subject to capital gains tax. This info is given in good faith and must not be relied upon when making any investment and/or trading decision(s). I hope this helps you make a fortune - if it does; then please remember me! "I'll give the TLDR answer. 1) You can't forecast the price direction. If you get it right you got lucky. If you think you get it right consistently you are either a statistical anomaly or a victim of confirmation bias. Countless academic studies show that you can not do this. 2) You reduce volatility and, importantly, left-tail risk by going to an index tracking ETF or mutual fund. That is, Probability(Gigantic Loss) is MUCH lower in an index tracker. What's the trade off? The good thing is there is NO tradeoff. Your expected return does not go down in the same way the risk goes down! 3) Since point (1) is true, you are wasting time analysing companies. This has the opportunity cost of not earning $ from doing paid work, which can be thought of as a negative return. ""With all the successful investors (including myself on a not-infrequent basis) going for individual companies directly"" Actually, academic studies show that individual investors are the worst performers of all investors in the stock market." "Of course, but that's not relevant to my example. Let me clarify: say you hold a highly-appreciated $10M position in AAPL and you have good reason to believe the next iPhone is going to be a flop, causing the stock to decline 20%. You can sell now to avoid the (probable) decline, but by doing so you will be left with, let's say, $6.67M after paying $3.33M of state and federal LTCG taxes on the appreciation ($9M of the $10M, because you bought a long time ago).  However, by simply doing nothing and ""eating"" the 20% decline, you'll end up with $8M instead of $6.67M.  Many economists would criticize the tax in this example, as it has led to the investor rationally suffering a $2M loss, instead of reallocating all $10M of his/her capital to a more promising enterprise. Furthermore, if/when many investors act that way, they can create inefficiency in the equity markets (prices not declining by as much as they should to reflect a firm's reduced prospects)." Unless other people believe you have a reason for selling at a lower price, your sale probably has no lasting effect at all on the market. Of course, if people see you dump a few million dollars' worth of shares at a discount, they may be inclined to believe you have a reason. But if you just sell a few, they will conclude the reason is just that you needed cash in a hurry.