Can after-hours trading affect options pricing?
Typically the settlement price for a financial instrument (such as AAPL stock) underlying a derivative contract is determined from the average price of trading in that instrument during some short time window specified by the exchange offering the derivative.  (Read the fine print on your contract to learn the exact date and time of that settlement period.) Because it's in an exchange's best interest to appear as fair as possible, the exchange will in general pick a high-volume period of time -- such as the close of trading on the expiry date -- in which to determine the settlement price. Now, the expiry date/time may be different from the last time at which the option can be traded, which may be different from the underlying settlement time.  For example, most US equity options currently expire on the Saturday following the third Friday of the month, whereas they can last be traded at end-of-day on the third Friday of the month, and the settlement period may be at a slightly different time on the third Friday of the month.  (Again, read the contract to know for sure.)  Moreover, your broker may demand to know whether you plan to exercise the option at an even earlier date/time. So, to answer your question: After-hours trading can only affect the settlement price of an underlying instrument if the exchange in question decides that the settlement period should happen during after-hours trading.  But since no exchange that wants to stay in business would possibly do that, the answer is no. Contract expiry time, contract exercise time, final contract trading time, and underlying settlement time may all fall at different dates/times.  The important one for your question is settlement time. "There is a white paper on ""The weekend effect of equity options"" it is a good paper and shows that (for the most part) option values do lose money from Friday to Monday. Which makes sense because it is getting closer to expiration. Of course this not something that can be counted on 100%.  If there is some bad news and the stock opens down on a Monday the puts would have increased and the calls decreased in value. Article Summary (from the authors): ""We find that returns on options on individual equities display markedly lower returns over weekends (Friday close to Monday close) relative to any other day of the week. These patterns are observed both in unhedged and delta-hedged positions, indicating that the effect is not the result of a weekend effect in the underlying securities. We find even stronger weekend effects in implied volatilities, but only after an adjustment to quote implied volatilities in terms of trading days rather than calendar days.""  ""Our results hold for puts and calls over a wide range of maturities and strike prices, for both equally weighted portfolios and for portfolios weighted by the market value of open interest, and also for samples that include only the most liquid options in the market. We find no evidence of a weekly seasonal in bid-ask spreads, trading volume, or open interest that could drive the effect. We also find little evidence that weekend returns are driven by higher levels of risk over the weekend.  ""The effect is particularly strong over expiration weekends, and it is also present to a lesser degree over mid-week holidays. Finally, the effect is stronger when the TED spread and market volatility are high, which we interpret as providing support for a limits to arbitrage explanation for the persistence of the effect."" - Christopher S. Jones & Joshua Shemes You can read more about this at this link for Memphis.edu"
"In short, yes. By ""forward selling"", you enter into a futures contract by which you agree to trade Euros for dollars (US or Singapore) at a set rate agreed to by both parties, at some future time. You are basically making a bet; you think that the dollar will gain on the Euro and thus you'd pay a higher rate on the spot than you've locked in with the future. The other party to the contract is betting against you; he thinks the dollar will weaken, and so the dollars he'll sell you will be worth less than the Euros he gets for them at the agreed rate. Now, in a traditional futures contract, you are obligated to execute it, whether it ends up good or bad for you. You can, to avoid this, buy an ""option"". By buying the option, you pay the other party to the deal for the right to say ""no, thanks"". That way, if the dollar weakens and you'd rather pay spot price at time of delivery, you simply let the contract expire un-executed. The tradeoff is that options cost money up-front which is now sunk; whether you exercise the option or not, the other party gets the option price. That basically creates a ""point spread""; you ""win"" if the dollar appreciates against the Euro enough that you still save money even after buying the option, or if the dollar depreciates against the Euro enough that again you still save money after subtracting the option price, while you ""lose"" if the exchange rates are close enough to what was agreed on that it cost you more to buy the option than you gained by being able to choose to use it." I asked a friend and he gave me a good explanation, so I'm just gonna paste it here for others: There is a simple and a complex answer depending on how much you want to understand the pricing dynamic of options.  LEAPs don't react 1:1 with a stock move because the probability of your option being in the money at expiry is still very much up in the air so you basically don't get full credit for a move in the stock this far out from expiry. The more complex answer involves a discussion of option 'greeks'.  Delta, Gamma, Theta, Vega, and Rho are variables that affect the pricing of all options.  The key greek in this case is Delta because it describes mathematically the expected move of an option as a ratio vs changes in stock price.  For put options the ratio is -1 to 0 where -1 is direct correlation between stock price and option price and 0 is no correlation.  The Delta increases as an option gets deeper in the money and also as it gets closer to expiry and reflects the probability of the option expiring in the money.  For your option contract the current Delta is -0.5673  so -3.38 * -0.5673 = 1.9 which is close.  Also keep in mind that that strike price had a last trade at 12:03 when the stock was at 13.3 and the current ask price is 22.30 so the last price isn't a true reflection of the market value.   As for the other greeks, Gamma is a reflection of volatility in the sense that it affects the rate of change of Delta as price and time changes.  Theta is the value of the time component of the option and is expressed as the expected time decay per day.  The problem is that the time premium is really some arbitrary number that the market maker seems to be able to change at will without justification and it can fluctuate wildly over short periods of time and I think this may explain some of the discrepancy.   If you bought the options when AAPL was $118.68 a couple weeks ago (option price of $18.85) and now AAPL is at $112.34 and the Delta over that time averaged at -0.55 then your expected option price would be $22.34 (($118.68 - $112.34) * 0.55 + 18.85 = $22.34) so you lost around $0.24 in time premium or 'Theta burn' over the last 2 weeks assuming it opens trading around 22.1 on Monday. Your broker should have information about the option contract greeks somewhere.  For my platform I have to put the cursor over top of the option contract for it to show me the greeks.  If your broker doesn't have this then you can get it from nasdaq.com. This is another reason that I only invest in deep in the money LEAPs because the time premium is much much lower than near the money and also because delta is much higher so if I want to trade out of it early I don't feel like I'm getting ripped off not getting paid for a stock price move.  For example look at the Jan 17 175 put.  The Delta is -0.9 and the time premium is only $0-1 depending if you are looking at the bid or ask.  The only downside is expected returns are lower for deep in the money contracts and they are expensive to buy. "Investopedia explains how a stock split impacts the stock's options: Each option contract is typically in control of 100 shares of an underlying security at a predetermined strike price. To find the new coverage of the option, take the split ratio and multiply by the old coverage (normally 100 shares). To find the new strike price, take the old strike price and divide by the split ratio. Say, for example, you own a call for 100 shares of XYZ with a strike price of $75. Now, if XYZ had a stock split of 2 for 1, then the option would now be for 200 shares with a strike price of $37.50. If, on the other hand, the stock split was 3 for 2, then the option would be for 150 shares with a strike price of $50. So, yes, a 2 for 1 stock split would halve the option strike prices.  Also, in case the Investopedia article isn't clear, after a split the options still control 100 shares per contract. Regarding how a dividend affects option prices, I found an article with a good explanation: As mentioned above, dividends payment could reduce the price of a stock due to reduction of the company's assets. It becomes intuitive to know that if a stock is expected to go down, its call options will drop in extrinsic value while its put options will gain in extrinsic value before it happens. Indeed, dividends deflate the extrinsic value of call options and inflate the extrinsic value of put options weeks or even months before an expected dividend payment.  Extrinsic value of Call Options are deflated due to dividends not only because of an expected reduction in the price of the stock but also due to the fact that call options buyers do not get paid the dividends that the stock buyers do. This makes call options of dividend paying stocks less attractive to own than the stocks itself, thereby depressing its extrinsic value. How much the value of call options drop due to dividends is really a function of its moneyness. In the money call options with high delta would be expected to drop the most on ex-date while out of the money call options with lower delta would be least affected. If a stock is expected to drop by a certain amount, that drop would already have been priced into the extrinsic value of its put options way beforehand. This is what happens to put options of dividend paying stocks. This effect is again a function of options moneyness but this time, in the money put options raise in extrinsic value more than out of the money put options. This is because in the money put options with delta of close to -1 would gain almost dollar or dollar on the drop of a stock. As such, in the money put options would rise in extrinsic value almost as much as the dividend rate itself while out of the money put options may not experience any changes since the dividend effect may not be strong enough to bring the stock down to take those out of the money put options in the money. So, no, a dividend of $1 will not necessarily decrease an option's price by $1 on the ex-dividend date.  It depends on whether it's a call or put option, and whether the option is ""in the money"" or ""out of the money"" and by how much." While open interest usually correlates to volume, the mark of liquidity is the bid ask spread. Even when trading options with spreads as large as an ask 2x the bid, a more realistic price that traders are willing to accept lies somewhere in the middle. Any option can easily be exited at intrinsic value: underlying price - exercise price for calls, exercise price - underlying price for puts.  For illiquid options, this will be the best price obtained.  For longer term options, something closer to the theoretical price is still possible. If an underlying is extremely liquid, yet the options aren't quite then options traders will be much more ready to trade at the theoretical price. For exiting illiquid options, small, < 4 contracts, and infrequent, > 30 minute intervals, orders are more likely to be filled closer to the theoretical price; however, if one's sells are the only trades, traders on the other side will take note and accept ever lowering implied volatilities. With knowledge of what traders will accept, it is always more optimal to trade out of options rather than exercise because of the added costs and uncertainty involved with exercising and liquidating. Today SPY (The S&P ETF) trades at $128. The option to buy at $140 (this is a Jan '13 call) trades for $5.  I buy the call, for $500 as they trade in 100 lots.  The S&P skyrockets to 1500 and SPY to $150. The call trades for $11, as it still has a month or two before expiring, so I sell it, and get $1100. The S&P rose 17%, but I doubled my money. If it 'only' rose 9%, to less than $140, I'd lose my investment. No, I don't need to buy the SPY I can sell the call any time before expiration. In fact, most options are not exercised, they are sold between purchase and expiration date. In my experience thanks to algorithmic trading the variation of the spread and the range of trading straight after a major data release will be as random as possible, since we live in an age that if some pattern existed at these times HFT firms would take out any opportunity within nanoseconds. Remember that some firms write algorithms to predict other algorithms, and it is at times like those that this strategy would be most effective. With regards to my own trading experience I have seen orders fill almost €400 per contract outside of the quoted range, but this is only in the most volatile market conditions. Generally speaking, event investing around numbers like these are only for top wall street firms that can use co-location servers and get a ping time to the exchange of less than 5ms. Also, after a data release the market can surge/plummet in either direction, only to recover almost instantly and take out any stops that were in its path. So generally, I would say that slippage is extremely unpredictable in these cases( because it is an advantage to HFT firms to make it so ) and stop-loss orders will only provide limited protection. There is stop-limit orders( which allow you to specify a price limit that is acceptable ) on some markets and as far as I know InteractiveBrokers provide a guaranteed stop-loss fill( For a price of course ) that could be worth looking at, personally I dont use IB.  I hope this answer provides some helpful information, and generally speaking, super-short term investing is for algorithms. What it means is that the stock has already moved down. Options and other derivatives follow the price of the underlying they are not a precursor to what the underlying is going to do. In other words, the price of a derivative is derived from the underlying. No, at least not noticeably so. The majority of what HFT does is to take advantage of the fact that there is a spread between buy and sell orders on the exchange, and to instantly fill both orders, gaining relatively risk-free profit from some inherent inefficiencies in how the market prices stocks. The end result is that intraday trading of the non-HFT nature, as well as speculative short-term trading will be less profitable, since HFT will cause the buy/sell spread to be closer than it would otherwise be. Buying and holding will be (largely) unaffected since the spread that HFT takes advantage of is miniscule compared to the gains a stock will experience over time.  For example, when you go to buy shares intending to hold them for a long time, the HFT might cost you say, 1 to 2 cents per share. When you go to sell the share, HFT might cost you the same again. But, if you held it for a long time, the share might have doubled or tripled in value over the time you held it, so the overall effect of that 2-4 cents per share lost from HFT is negligible. However, since the HFT is doing this millions of times per day, that 1 cent (or more commonly a fraction of a cent) adds up to HFTs making millions. Individually it doesn't affect anyone that much, but collectively it represents a huge loss of value, and whether this is acceptable or not is still a subject of much debate!