Exercising an option without paying for the underlying
This is dependent on the broker according to The Options Industry Council.  Your broker will specify what they would do upon expiry (or hours before last trade) if you did not indicate your preference. Most likely they will conduct a probabilistic simulation to see whether exercising the contracts may result in margin deficit even after selling the delivered shares under extreme circumstances. In most cases, brokers tend to liquidate the option for you (sell to close) before expiry.  I've seen people complain about certain brokers forcing liquidation at terrible bid-ask spreads even though the options are still days to expiry. It is better for you to close the position on your own beforehand. The best brokers would allow margin deficit and let you deposit the required amount of money afterward.  Please consult your broker's materials. If you can't find them, use live chat or email tickets. It would be nice if the broker could be instructed to clear out the position for you, but in my experience the broker will simply give you the shares that you can't afford, then freeze your account because you are over your margin limit, and issue a margin call. This happened to me recently because of a dumb mistake: options I paid $200 for and expected to expire worthless, ended up slightly ITM, so they were auto-exercised on Friday for about $20k, and my account was frozen (only able to close positions).  By the next Monday, market news had shifted the stock against me and I had to sell it at a loss of $1200 to meet the margin call.  This kind of thing is what gives option trading a reputation for danger: A supposedly max-$200-risk turned into a 6x greater loss.  I see no reason to ever exercise, I always try to close my positions, but these things can happen. "Unless you want to own the actual shares, you should simply sell the call option.By doing so you actual collect the profits (including any remaining time-value) of your position without ever needing to own the actual shares. Please be aware that you do not need to wait until maturity of the call option to sell it. Also the longer you wait, more and more of the time value embedded in the option's price will disappear which means your ""profit"" will go down." As other answers state, selling the options contracts to the market is a definite way out, and probably the best in most cases.  If you're determined to exercise your options (or there's not enough liquidity to reasonably sell your contracts to the market), then you could plan ahead and exercise smaller number of contracts at a time and sell the resulting position in the underlying, which will give you funds to exercise some more contracts and sell the underlying.    If you think you're going down this path, however, make sure that you take into account your broker's rules for settlement.  You may need to start the exercise / sell cycle before the option's expiration date.
I have held an in the money long position on an option into expiration, on etrade, and nothing happened.   (Scalping expiring options - high risk) The option expired a penny or two ITM, and was not worth exercising, nor did I have the purchasing power to exercise it. (AAPL) From etrade's website: Here are a few things to keep in mind about exercises and assignments: Equity options $0.01 or more in the money will be automatically   exercised for you unless you instruct us not to exercise them. For   example, a September $25 call will be automatically exercised if the   underlying security's closing price is $25.01 or higher at expiration.   If the closing price is below $25.01, you would need to call an   E*TRADE Securities broker at 1-800-ETRADE-1 with specific instructions   for exercising the option. You would also need to call an E*TRADE   Securities broker if the closing price is higher than $25.01 at   expiration and you do not wish to exercise the call option. Index   options $0.01 or more in the money will be automatically exercised for   you unless you instruct us not to exercise them. Options that are out   of the money will expire worthless. You may request to exercise   American style options anytime prior to expiration. A request not to   exercise options may be made only on the last trading day prior to   expiration. If you'd like to exercise options or submit   do-not-exercise instructions, call an E*TRADE Securities broker at   1-800-ETRADE-1. You won't be charged our normal fee for   broker-assisted trades, but the regular options commission will apply.   Requests are processed on a best-efforts basis.  When equity options are exercised or assigned, you'll receive a Smart   Alert message letting you know. You can also check View Orders to see   which stock you bought or sold, the number of shares, and the strike   price.  Notes: If you do not have sufficient purchasing power in your account   to accept the assignment or exercise, your expiring options positions   may be closed, without notification, on the last trading day for the   specific options series. Additionally, if your expiring position is   not closed and you do not have sufficient purchasing power, E*TRADE   Securities may submit do-not-exercise instructions without   notification. Find out more about options expiration dates. For listed options in NYSE,CBOE, is it possible for an option holder to exercise an option even if it is not in the money?  Abandonment of in-the-money options or the exercise of out-of-the-money options are referred as contrarian instructions. They are sometimes forbidden, e.g. see CME - Weekly & End-of-Month (EOM) Options on Standard & E-mini S&P 500 Futures  (mirror): In addition to offering European-style alternatives (which by definition can only be exercised on expiration day), both the weekly and EOM options prohibit contrarian instructions (the abandonment of in-the-money options, or the exercise of out-of-the-money options). Thus, at expiration, all in-the-money options are automatically exercised, whereas all options not in-the-money are automatically abandoned. When you can exercie your option depends on your trading style. In the american options trading style (the most popular) you're allowed to exercice your options and make profit (if any) whenever you want before the expiration date. Thus, the decision of  exercising your option and make a profit out of it does not rely only on the asset price. The reason is, you already paid for the premium to get the option. So, if taken into account the underlying price AND your premium, your investment is profitable then you can exercice your contract anytime. "Yes, if it's an American style option. American style options may be exercised at any time prior to expiration (even if they're not in-the-money). Generally, you are required to deliver or accept delivery of the underlying by the beginning of the next trading day. If you are short, you may be chosen by the clearinghouse to fulfill the exercise (a process called ""assignment""). Because the clearinghouse is the counter-party to every options trade, you can be assigned even if the specific person who purchased the option you wrote didn't exercise, but someone else who holds a long position did. Similarly, you might not be assigned if that person did exercise. The clearinghouse randomly chooses a brokerage to fulfill an assignment, and the brokerage will randomly choose an individual account. If you're going to be writing options, especially using spreads, you need to have a plan ahead of time on what to do if one of your legs gets assigned. This is more likely to happen just before a dividend payment, if the payment is more than the remaining time value." "I'm adding to @Dilip's basic answer, to cover the additional points in your question.  I'll assume you are referring to publicly traded stock options, such as those found on the CBOE, and not an option contract entered into privately between two specific counterparties (e.g. as in an employer stock option plan). Since you are not obligated to exercise a call option you purchased on the market, you don't need to maintain funds on account for possible exercising.  You could instead let the option expire, or resell the option, neither of which requires funds available for purchase of the underlying shares. However, should you actually choose to exercise the call option (and usually this is done close to expiration, if at all), you will be required to fund your account much like if you bought the underlying shares in the first place.  Call your broker to determine the exact rules and timing for when they need the money for a call-option exercise. And to expand on the idea of ""cancelling"" an option you purchased: No, you cannot ""cancel"" an option contract, per se.  But, you are permitted to sell the call option to somebody else willing to buy, via the market.  When you sell your call option, you'll either make or lose money on the sale – depending on the price of the underlying shares at the time (are they in- or out- of the money?), volatility in the market, and remaining time value.  Once you sell, you're back to ""no position"".  That's not the same as ""cancelled"", but you are out of the trade, whether at profit or loss. Furthermore, the option writer (i.e. the seller who ""sold to open"" a position, in writing the call in the first place) is also not permitted to cancel the option he wrote.  However, the option writer is permitted to close out the original short position by simply buying back a matching call option on the market.  Again, this would occur at either profit or loss based on market prices at the time.  This second kind of buy order – i.e. made by someone who initially wrote a call option – is called a ""buy to close"", meaning the purchase of an offsetting position.  (The other kind of buy is the ""buy to open"".) Then, consider: Since an option buyer is free to re-sell the option purchased, and since an option writer (who ""sold to open"" the new contract) is also free to buy back an offsetting option, a process known as clearing is required to match remaining buyers exercising the call options held with the remaining option writers having open short positions for the contract.  For CBOE options, this clearing is performed by the Options Clearing Corporation.  Here's how it works (see here): What is the OCC? The Options Clearing Corporation is the sole issuer of all securities   options listed at the CBOE, four other U.S. stock exchanges and the   National Association of Securities Dealers, Inc. (NASD), and is the   entity through which all CBOE option transactions are ultimately   cleared. As the issuer of all options, OCC essentially takes the   opposite side of every option traded. Because OCC basically becomes   the buyer for every seller and the seller for every buyer, it allows   options traders to buy and sell in a secondary market without having   to find the original opposite party.   [...]   [emphasis above is mine] When a call option writer must deliver shares to a call option buyer exercising a call, it's called assignment.  (I have been assigned before, and it isn't pleasant to see a position called away that otherwise would have been very profitable if the call weren't written in the first place!) Also, re: ""I know my counter party cannot sell his shares"" ... that's not strictly true.  You are thinking of a covered call.  But, an option writer doesn't necessarily need to own the underlying shares.  Look up Naked call (Wikipedia).  Naked calls aren't frequently undertaken because a naked call ""is one of the riskiest options strategies because it carries unlimited risk"".  The average individual trader isn't usually permitted by their broker to enter such an order, but there are market participants who can do such a trade. Finally, you can learn more about options at The Options Industry Council (OIC)." In Australia there are 2 type of warrants (I don't know if it is the same in the US, UK and other countries), the first are trading warrants and the second are instalment warrants. The trading warrants are exactly what it says, they are used for trading. They are similar to option and have calls and puts. As Cameron says, they differ from exchange traded options in that they are issued by the financial companies whereas options are generally written by other investors. Instalment warrants on the other hand are usually bought and sold by investors with a longer term view. There are no calls and puts and you can just go long with them. They are also issued by financial companies, and how they work is best explained through an example: if I was to buy a stock directly say I would be paying $50 per share, however an instalment warrant in the underlying stock may be offered for $27 per warrant. I could buy the warrant directly from the company when it is issued or on the secondary market just like shares. I would pay the $27 per warrant upfront, and then in 2 years time when the warrant expires I have the choice to purchase the underlying stock for the strike price of say $28, roll over to a new issue of warrants, sell it back on the secondary market, or let it expire, in which case I would receive any intrinsic value left in the warrant. You would have noticed that the warrant purchase price plus the strike price adds up to more than the share price ($55 compared to $50). This is the interest component inherent in the warrant which covers the borrowing costs until expiry, when you pay the second portion (the strike price) and receive the underlying shares. Another difference between Instalment warrants and trading warrants (and options) is that with instalment warrants you still get the full dividends just like the shares, but at a higher yield than the shares. "Alternatively you could exercise 12000 shares for $36000 and immediately sell 7200 shares to recover your exercise price. Then you use the remaining 4800 share to pay the exercise price of the remaining 8000 options. Both scenarios are equivalent but may have different fees associated, so it's worth checking the fine print.  Tax wise: The above example is ""cash neutral before taxes"". The taxes associated with these transaction are substantial, so it's highly recommended to talk with a tax adviser. ""cash neutral after taxes"" depends highly on your specific tax situation." I've never heard of an employer offering this kind of arrangement before, so my  answer assumes there is no special tax treatment that I'm not aware of. Utilizing the clause is probably equivalent to exercising some of your options, selling the shares back to your employer at FMV, and then exercising more options with the proceeds. In this case if you exercise 7500 shares and sell them back at FMV, your proceeds would be 7500 x $5 = $37,500, with which you could exercise the remaining 12,500 options. The tax implications would be (1) short-term capital gains of 7500 x ($5 - $3) = $15,000 and (2) AMT income of 12,500 x ($5 - $3) = $25,000, assuming you don't sell the shares within the calendar year.