When an in-the-money stock option expires does the broker always execute it or does its value become worthless if the owner doesn't execute it?
It depends on the broker, each one's rules may vary. Your broker should be able to answer this question for how they handle such a situation. The broker I used would execute and immediately sell the stock if the option was 25 cents in the money at expiration. If they simply executed and news broke over the weekend (option expiration is always on Friday), the client could wake up Monday to a bad margin call, or worse.
Options reflect expectations about the underlying asset, and options are commonly priced using the Black-Scholes model:  N(d1) and N(d2) are probability functions, S is the spot (current) price of the asset, K is the strike price, r is the risk free rate, and T-t represents time to maturity.  Without getting into the mathematics, it suffices to say that higher volatility or expectation of volatility increases the perceived riskiness of the asset, so call options are priced lower  and put options are priced higher. Think about it intuitively. If the stock is more likely to go downwards, then there's an increased chance that the call option expires worthless, so call options must be priced lower to accommodate the relative change in expected value of the option.  Puts are priced similarly, but they move inversely with respect to call option prices due to Put-Call parity. So if call option prices are falling, then put option prices are rising (Note, however, that call prices falling does not cause put prices to rise. The inverse relationship exists because of changes in the underlying factors and how pricing works.) So the option action signifies that the market believes the stock is headed lower (in the given time frame). That does not mean it will go lower, and option traders assume risk whenever they take a particular position. Bottom line: gotta do your own homework! Best of luck. Technically, of course. Almost any company can go bankrupt. One small note: a company goes bankrupt, not its stock. Its stock may become worthless in bankruptcy, but a stock disappearing or being delisted doesn't necessarily mean the company went bankrupt. Bankruptcy has implications for a company's debt as well, so it applies to more than just its stock. I don't know of any historical instances where this has happened, but presumably, the warning signs of bankruptcy would be evident enough that a few things could happen.  Another company, e.g. another exchange, holding firm, etc. could buy out the exchange that's facing financial difficulty, and the companies traded on it would transfer to the new company that's formed. If another exchange bought out the struggling exchange, the shares of the latter could transfer to the former. This is an attractive option because exchanges possess a great deal of infrastructure already in place. Depending on the country, this could face regulatory scrutiny however. Other firms or governments could bail out the exchange if no one presented a buyout offer. The likelihood of this occurring depends on several factors, e.g. political will, the government(s) in question, etc. For a smaller exchange, the exchange could close all open positions at a set price. This is exactly what happened with the Hong Kong Mercantile Exchange (HKMex) that MSalters mentioned. When the exchange collapsed in May 2013, it closed all open positions for their price on the Thursday before the shutdown date. I don't know if a stock exchange would simply close all open positions at a set price, since equity technically exists in perpetuity regardless of the shutdown of an exchange, while many derivatives have an expiration date. Furthermore, this might not be a feasible option for a large exchange. For example, the Chicago Mercantile Exchange lists thousands of products and manages hundreds of millions of transactions, so closing all open positions could be a significant undertaking.  If none of the above options were available, I presume companies listed on the exchange would actively move to other, more financially stable exchanges. These companies wouldn't simply go bankrupt. Contracts can always be listed on other exchanges as well. Considering the high level of mergers and acquisitions, both unsuccessful and successful,  in the market for exchanges in recent years, I would assume that option 1 would be the most likely (see the NYSE Euronext/Deutsche Börse merger talks and the NYSE Euronext/ICE merger that's currently in progress), but for smaller exchanges, there is the recent historical precedent of the HKMex that speaks to #3. Also, the above answer really only applies to publicly traded stock exchanges, and not all stock exchanges are publicly-held entities. For example, the Shanghai Stock Exchange is a quasi-governmental organization, so I presume option 2 would apply because it already receives government backing. Its bankruptcy would mean something occurred for the government to withdraw its backing or that it became public, and a discussion of those events occurring in the future is pure speculation. I'm sorry, but your math is wrong.  You are not equally likely to make as much money by waiting for expiration. Share prices are moving constantly in both directions.  Very rarely does any stock go either straight up or straight down.  Consider a stock with a share price of $12 today.  Perhaps that stock is a bad buy, and in 1 month's time it will be down to $10.  But the market hasn't quite wised up to this yet, and over the next week it rallies up to $15. If you bought a European option (let's say an at-the-money call, expiring in 1 month, at $12 on our start date), then you lost.  Your option expired worthless. If you bought an American option, you could have exercised it when the share price was at $15 and made a nice profit. Keep in mind we are talking about exactly the same stock, with exactly the same history, over exactly the same time period.  The only difference is the option contract.  The American option could have made you money, if you exercised it at any time during the rally, but not the European option - you would have been forced to hold onto it for a month and finally let it expire worthless. (Of course that's not strictly true, since the European option itself can be sold while it is in the money - but eventually, somebody is going to end up holding the bag, nobody can exercise it until expiration.) The difference between an American and European option is the difference between getting N chances to get it right (N being the number of days 'til expiration) and getting just one chance.  It should be easy to see why you're more likely to profit with the former, even if you can't accurately predict price movement. "The market capitalization of a stock is the number of shares outstanding (of each stock class), times the price of last trade (of each stock class). In a liquid market (where there are lots of buyers and sellers at all price points), this represents the price that is between what people are bidding for the stock and what people are asking for the stock.  If you offer any small amount more than the last price, there will be a seller, and if you ask any small amount less than the last price, there will be a buyer, at least for a small amount of stock. Thus, in a liquid market, everyone who owns the stock doesn't want to sell at least some of their stock for a bit less than the last trade price, and everyone who doesn't have the stock doesn't want to buy some of the stock for a bit more than the last trade price. With those assumptions, and a low-friction trading environment, we can say that the last trade value is a good midpoint of what people think one share is worth.  If we then multiply it by the number of shares, we get an approximation of what the company is worth. In no way, shape or form does it not mean that there is 32 billion more invested in the company, or even used to purchase stock. There are situations where a 32 billion market cap swing could mean 32 billion more money was invested in the company: the company issues a pile of new shares, and takes in the resulting money.  People are completely neutral about this gathering in of cash in exchange for dilluting shares.  So the share price remains unchanged, the company gains 32 billion dollars, and there are now more shares outstanding. Now, in some sense, there is zero dollars currently invested in a stock; when you buy a stock, you no longer have the money, and the money goes to the person who no longer has the stock. The issue here is the use of the continuous tense of ""invested in""; the investment was made at some point, but the money doesn't really stay in this continuous state of being.  Unless you consider the investment liquid, and the option to take money out being implicit, it being a continuous action doesn't make much sense. Sometimes the money is invested in the company, when the company causes stocks to come into being and sells them. The owners of stocks has invested money in stocks in that they spent that money to buy the stocks, but the total sum of money ever spent on stocks for a given company is not really a useful value. The market capitalization is an approximation, which under the efficient market hypothesis (that markets find the correct price for things nearly instantly) is reasonably accurate, of the value the company has collectively to its shareholders.  The efficient market hypothesis isn't accurate, but it is an acceptable rule of thumb. Now, this value -- market capitalization -- is arguably not the total value of a company: other stakeholders include bond holders, labour, management, various contract counter-parties, government and customers.  Some companies are structured so that almost all value is captured not by the stock owners, but by contract counter-parties (this is sometimes used for hiding assets or debts). But for most large publically traded companies, it (in theory) shouldn't be far off." At the higher level - yes. The value of an OTM (out of the money) option is pure time value. It's certainly possible that when the stock price gets close to that strike, the value of that option may very well offer you a chance to sell at a profit. Look at any OTM strike bid/ask and see if you can find the contract low for that option. Most will show that there was an opportunity to buy it lower at some point in the past.  Your trade. Ask is meaningless when you own an option. A thinly traded one can be bid $0 /ask $0.50. What is the bid on yours? "If the owner of the stock wants it back, they ""call"" it back. There are no guarantees of how long you can keep it for your short, or the cost involved to hold it.  Usually, everyone knows about a particular set-up (e.g. a warrant or convertible bond mispricing) that is attractive for arbitrage. This causes the associated stock to be in high demand thus expensive to borrow for shorting, or impossible to find for any price at all." "Am I getting it right that in India in terms of short selling in F&O market its what in the rest of the world is called naked short and you actually make promise to depositary that you will deliver that security you sold on settlement without actually owning the security or going through SLB mechanism? In Future and Options; there is no concept of short selling. You buy a future for a security / index. On the settlement day; the exchange determines the settlement price. The trade is closed in cash. i.e. Based on the settlement price, you [and the other party] will either get money [other party looses money] or you loose money [other party gets the money]. Similarly for Options; on expiry, the all ""In Money"" [or At Money] Options are settled in cash and you are credit with funds [the option writer is debited with funds]. If the option is ""out of money"" it expires and you loose the premium you paid to exercise the option." You are NOT responsible for liquidating the position.  You will either end up retaining your 100 sh. after expiration, or they will be called away automatically. You don't have to do anything.  Extending profitability can mean different things, but a major consideration is whether or not you want to hold the stock or not.  If so, you can buy back the in-the-money call and sell another one at-the-money, or further out. There are lots of options.