What is the meaning of “short selling” or “going short” a stock?
This is a gross simplification as there are a few different ways to do this. The principle overall is the same though. To short a stock, you borrow X shares from a third party and sell them at the current price. You now owe the lender X shares but have the proceeds from the sale. If the share price falls you can buy back those shares at the new lower price, return them to the lender and pocket the difference. The risk comes when the share price goes the other way, you now owe the lender the new value of the shares, so have to find some way to cover the difference. This happened a while back when Porsche made a fortune buying shares in Volkswagen from short sellers, and the price unexpectedly rose. Rich's answer captures the basic essence of short selling with example. I'd like to add these additional points: You typically need a specially-privileged brokerage account to perform short selling.  If you didn't request short selling when you opened your account, odds are good you don't have it, and that's good because it's not something most people should ever consider doing.  Short selling is an advanced trading strategy.  Be sure you truly grok selling short before doing it. Consider that when buying stock (a.k.a. going long or taking a long position, in contrast to short) then your potential loss as a buyer is limited (i.e. stock goes to zero) and your potential gain unlimited (stock keeps going up, if you're lucky!)   Whereas, with short selling, it's reversed: Your loss can be unlimited (stock keeps going up, if you're unlucky!) and your potential gain is limited (i.e. stock goes to zero.)   The proceeds you receive from a short sale – and then some – need to stay in your account to offset the short position.  Brokers require this.  Typically, margin equivalent to 150% the market value of the shares sold short must be maintained in the account while the short position is open. The owner of the borrowed shares is still expecting his dividends, if any.  You are responsible for covering the cost of those dividends out of your own pocket.  To close or cover your short position, you initiate a buy to cover.  This is simply a buy order with the intention that it will close out your matching short position.   You may be forced to cover your short position before you want to and when it is to your disadvantage!  Even if you have sufficient margin available to cover your short, there are cases when lenders need their shares back.  If too many short sellers are forced to close out positions at the same time, they push up demand for the stock, increasing price and deepening their losses.  When this happens, it's called a short squeeze. In the eyes of the public who mostly go long buying stock, short sellers are often reviled. However, some people and many short sellers believe they are providing balance to the market and preventing it sometimes from getting ahead of itself. [Disambiguation: A short sale in the stock market is not related to the real estate concept of a short sale, which is when a property owner sells his property for less than he owes the bank.] Additional references: The 'normal' series of events when trading a stock is to buy it, time passes, then you sell it. If you believe the stock will drop in price, you can reverse the order, selling shares, waiting for the price drop, then buying them back. During that time you own say, -100 shares, and are 'short' those shares. "The reason for selling a stock ""short"", is for when you believe the stock value will decrease in the near future. Here is an example: Today Exxon-Mobile stock is selling for $100 / share. You are expecting the price to decrease, so you want to short the stock, which means your broker (i.e. eTrade, etc) allows you to borrow shares without paying money, and those shares are transferred into your account, and then you sell them and receive money for the sale. But you didn't actually own those shares, you only borrowed them, so you need to return the shares to your broker sometime in the future.  Let's say you borrow 10 shares @ $100, and you sell them at the market price of $100, you receive $1,000 in your account. But you owe your broker 10 shares, which you need to return sometime in the future. A few days later, the share price has decreased to $80. Now you can buy 10 shares from the market at a total cost of $800. You get 10 shares, and return those shares to your broker. Since you originally took in $1,000, and you just paid out $800, you keep a resulting profit of $200"
"The question is, how do I exit? I can't really sell the puts because there isn't   enough open interest in them now that they are so far out of the money. I have about $150K of funds outside of this position that I could use, but I'm   confused by the rules of exercising a put. Do I have to start shorting the stock? You certainly don't want to give your broker any instructions to short the stock! Shorting the stock at this point would actually be increasing your bet that the stock is going to go down more. Worse, a short position in the stock also puts you in a situation of unlimited risk on the stock's upside – a risk you avoided in the first place by using puts. The puts limited your potential loss to only your cost for the options. There is a scenario where a short position could come into play indirectly, if you aren't careful.  If your broker were to permit you to exercise your puts without you having first bought enough underlying shares, then yes, you would end up with a short position in the stock. I say ""permit you"" because most brokers don't allow clients to take on short positions unless they've applied and been approved for short positions in their account. In any case, since you are interested in closing out your position and taking your profit, exercising only and thus ending up with a resulting open short position in the underlying is not the right approach. It's not really a correct intermediate step, either. Rather, you have two typical ways out: Sell the puts.  @quantycuenta has pointed out in his answer that you should be able to sell for no less than the intrinsic value, although you may be leaving a small amount of time value on the table if you aren't careful.  My suggestion is to consider using limit orders and test various prices approaching the intrinsic value of the put.  Don't use market orders where you'll take any price offered, or you might be sorry. If you have multiple put contracts, you don't need to sell them all at once. With the kind of profit you're talking about, don't sweat paying a few extra transactions worth of commission. Exercise the puts.  Remember that at the other end of your long put position is one (or more) trader who wrote (created) the put contract in the first place. This trader is obligated to buy your stock from you at the contract price should you choose to exercise your option.  But, in order for you to fulfill your end of the contract when you choose to exercise, you're obligated to deliver the underlying shares in exchange for receiving the option strike price. So, you would first need to buy underlying shares sufficient to exercise at least one of the contracts.  Again, you don't need to do this all at once.  @PeterGum's answer has described an approach. (Note that you'll lose any remaining time value in the option if you choose to exercise.) Finally, I'll suggest that you ought to discuss the timing and apportioning of closing out your position with a qualified tax professional. There are tax implications and, being near the end of the year, there may be an opportunity* to shift some/all of the income into the following tax year to minimize and defer tax due. * Be careful if your options are near expiry!  Options typically expire on the 3rd Friday of the month." Typically this isn't a random order- having a small volume just means it's not showing on the chart, but it is a vlid price point. Same thing would've happened if it would've been a very large order that shows on the chart. Consider also that this could have been the first one of many transactions that go far below your stop point - would you not have wanted it to be executed then, at this time, as it did? Would you expect the system to look into future and decide that this is a one time dip, and not sell; versus it is a crash, and sell? Either way, the system cannot look in the future, so it has no way to know if a crash is coming, or if it was a short dip; therefore the instrcutions are executed as given - sell if any transfer happens below the limit. To avoid that (or at least reduce the chance for it), you can either leave more distance (and risk a higher loss when it crashes), or trade higher volumes, so the short small dip won't execute your order; also, very liquid stocks will not show such small transaction dips. "I'm just trying to visualize the costs of trading. Say I set up an account to trade something (forex, stock, even bitcoin) and I was going to let a random generator determine when I should buy or sell it. If I do this, I would assume I have an equal probability to make a profit or a loss. Your question is what a mathematician would call an ""ill-posed problem.""  It makes it a challenge to answer.  The short answer is ""no.""  We will have to consider three broad cases for types of assets and two time intervals. Let us start with a very short time interval.  The bid-ask spread covers the anticipated cost to the market maker of holding an asset bought in the market equal to the opportunity costs over the half-life of the holding period.  A consequence of this is that you are nearly guaranteed to lose money if your time interval between trades is less than the half-life of the actual portfolio of the market maker.  To use a dice analogy, imagine having to pay a fee per roll before you can gamble.  You can win, but it will be biased toward losing. Now let us go to the extreme opposite time period, which is that you will buy now and sell one minute before you die.  For stocks, you would have received the dividends plus any stocks you sold from mergers.  Conversely, you would have had to pay the dividends on your short sales and received a gain on every short stock that went bankrupt.  Because you have to pay interest on short sales and dividends passed, you will lose money on a net basis to the market maker.  Maybe you are seeing a pattern here.  The phrase ""market maker"" will come up a lot. Now let us look at currencies.  In the long run, if the current fiat money policy regime holds, you will lose a lot of money.  Deflation is not a big deal under a commodity money regime, but it is a problem under fiat money, so central banks avoid it.  So your long currency holdings will depreciate.  Your short would appreciate, except you have to pay interest on them at a rate greater than the rate of inflation to the market maker. Finally, for commodities, no one will allow perpetual holding of short positions in commodities because people want them delivered.  Because insider knowledge is presumed under the commodities trading laws, a random investor would be at a giant disadvantage similar to what a chess player who played randomly would face against a grand master chess player.  There is a very strong information asymmetry in commodity contracts.  There are people who actually do know how much cotton there is in the world, how much is planted in the ground, and what the demand will be and that knowledge is not shared with the world at large.  You would be fleeced. Can I also assume that probabilistically speaking, a trader cannot do   worst than random? Say, if I had to guess the roll of a dice, my   chance of being correct can't be less than 16.667%. A physicist, a con man, a magician and a statistician would tell you that dice rolls and coin tosses are not random.  While we teach ""fair"" coins and ""fair"" dice in introductory college classes to simplify many complex ideas, they also do not exist.  If you want to see a funny version of the dice roll game, watch the 1962 Japanese movie Zatoichi.  It is an action movie, but it begins with a dice game.   Consider adopting a Bayesian perspective on probability as it would be a healthier perspective based on how you are thinking about this problem.  A ""frequency"" approach always assumes the null model is true, which is what you are doing.  Had you tried this will real money, your model would have been falsified, but you still wouldn't know the true model. Yes, you can do much worse than 1/6th of the time.  Even if you are trying to be ""fair,"" you have not accounted for the variance. Extending that logic, then for an inexperienced trader, is it right to   say then that it's equally difficult to purposely make a loss then it   is to purposely make a profit? Because if I can purposely make a loss,   I would purposely just do the opposite of what I'm doing to make a   profit. So in the dice example, if I can somehow lower my chances of   winning below 16.6667%, it means I would simply need to bet on the   other 5 numbers to give myself a better than 83% chance of winning. If the game were ""fair,"" but for things like forex the rules of the game are purposefully changed by the market maker to maximize long-run profitability.  Under US law, forex is not regulated by anything other than common law.  As a result, the market maker can state any price, including prices far from the market, with the intent to make a system used by actors losing systems, such as to trigger margin calls.  The prices quoted by forex dealers in the US move loosely with the global rates, but vary enough that only the dealer should make money systematically.  A fixed strategy would promote loss. You are assuming that only you know the odds and they would let you profit from your 83.33 percentage chance of winning. So then, is the costs of trading from a purely probabilistic point of   view simply the transaction costs? 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? No, the cost of trading is the opportunity cost of the money.  The transaction costs are explicit costs, but you have ignored the implicit costs of foregone interest and foregone happiness using the money for other things. You will want to be careful here in understanding probability because the distribution of returns for all of these assets lack a first moment and so there cannot be a ""mean return.""  A modal return would be an intellectually more consistent perspective, implying you should use an ""all-or-nothing"" cost function to evaluate your methodology." 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. "The process of borrowing shares and selling them is called shorting a stock, or ""going short.""  When you use money to buy shares, it is called ""going long."" In general, your strategy of going long and short in the same stock in the same amounts does not gain you anything.  Let's look at your two scenarios to see why. When you start, LOOT is trading at $20 per share.  You purchased 100 shares for $2000, and you borrowed and sold 100 shares for $2000.  You are both long and short in the stock for $2000.  At this point, you have invested $2000, and you got your $2000 back from the short proceeds.  You own and owe 100 shares. Under scenario A, the price goes up to $30 per share.  Your long shares have gone up in value by $1000.  However, you have lost $1000 on your short shares.  Your short is called, and you return your 100 shares, and have to pay interest.  Under this scenario, after it is all done, you have lost whatever the interest charges are. Under scenario B, the prices goes down to $10 per share.  Your long shares have lost $1000 in value.  However, your short has gained $1000 in value, because you can buy the 100 shares for only $1000 and return them, and you are left with the $1000 out of the $2000 you got when you first sold the shorted shares.  However, because your long shares have lost $1000, you still haven't gained anything.  Here again, you have lost whatever the interest charges are. As explained in the Traders Exclusive article that @RonJohn posted in the comments, there are investors that go long and short on the same stock at the same time.  However, this might be done if the investor believes that the stock will go down in a short-term time frame, but up in the long-term time frame.  The investor might buy and hold for the long term, but go short for a brief time while holding the long position. However, that is not what you are suggesting.  Your proposal makes no prediction on what the stock might do in different periods of time.  You are only attempting to hedge your bets.  And it doesn't work.  A long position and a short position are opposites to each other, and no matter which way the stock moves, you'll lose the same amount with one position that you have gained in the other position.  And you'll be out the interest charges from the borrowed shares every time. With your comment, you have stated that your scenario is that you believe that the stock will go up long term, but you also believe that the stock is at a short-term peak and will drop in the near future.  This, however, doesn't really change things much.  Let's look again at your possible scenarios. You believe that the stock is a long-term buy, but for some reason you are guessing that the stock will drop in the short-term.  Under scenario A, you were incorrect about your short-term guess.  And, although you might have been correct about the long-term prospects, you have missed this gain.  You are out the interest charges, and if you still think the stock is headed up over the long term, you'll need to buy back in at a higher price. Under scenario B, it turns out that you were correct about the short-term drop.  You pocket some cash, but there is no guarantee that the stock will rise anytime soon.  Your investment has lost value, and the gain that you made with your short is still tied up in stocks that are currently down. Your strategy does prevent the possibility of the unlimited loss inherent in the short.  However, it also prevents the possibility of the unlimited gain inherent in the long position.    And this is a shame, since you fundamentally believe that the stock is undervalued and is headed up.  You are sabotaging your long-term gains for a chance at a small short-term gain." Ideally, stock price reflects the value of the company, the dividends it is expected to pay, and what people expect the future value of the company to be. Only one of those (maybe one and a half) is related to current  sales, and not always directly. Short-term motion of a stock is even less directly linked, since it also reflects previous expectations. A company can announce disappointing sales and see its stock go up, if the previous price was based on expecting  worse news. This is the bird's eye view of how shorting works: When you place an order to sell a stock short, your broker attempts to grab the desired number of shares from any accounts of its other customers and makes them available for you to sell. If no other customers own shares of this stock, then generally you are out of luck (It is more complicated like that in practice, but this is just an overview).    Your odds are better if the particular stock has a large float (i.e. a large number of shares that are actually available for trading) and its short ratio is low (which means relatively few shares   are currently being sold short). Also, a large brokerage may be more likely to have access to the shares than a small niche-market broker.   The example you've given, Angie's List (ANGI) is a $600M small-cap with a comparatively low float, and though I haven't been able to glean the short ratio, it appears that a lot of investors are bearish on this stock and probably already had the same idea to short it.  There is really no way to find out if a specific broker has shares in inventory available for shorting, short of (forgive the pun) checking directly with the broker. Thanks for your reply. I’m not familiar with the term “Held-For-Trading Security”. My securities are generally held as collateral against my shorts. To clarify, I am just trying to track the “money in” and “money out” entries in my account for the shorts I write. The transaction is relatively straight forward, except there is a ton of information attached! In simple terms, for the ticker CSR and short contract CSRUQ8, the relevant entries look something like this: There are no entries for expiries. I need to ensure that funds are available for future margin calls and assignments. The sale side using covered calls is as involved.