Does an option trading below parity always indicate an arbitrage opportunity?
"Probably but not necessarily.  Your question could also be posed regarding cash & carry for commodities in contango: If I can take delivery on the gold now, short the gold next year and make delivery then, paying the storage fees, is this an arbitrage opportunity? It is in the sense that you know your delivery and the money you will make, but it's not in the sense that until delivery (or execution in the options case) you are still on the hook for the margins due from price fluctuations. Additionally you need to consider what ROI you will make from the trade. Even though it's ""guaranteed"" it may be less than what you can earn from other ""zero risk"" opportunities." "Defining parity as ""parity is the amount by which an option is in the money"", I'd say there may be an arbitrage opportunity. If there's a $50 strike on a stock valued at $60 that I can buy for less than $10, there's an opportunity.  Keep in mind, options often show high spreads, my example above might show a bid/ask of $9.75/$10.25, in which case the last trade of $9.50 should be ignored in favor of the actual ask price you'd pay.  Mispricing can exist, but in this day and age, is far less likely." In the equity world, if a stock trades at 110 and is going to pay a dividend of 10 in a few days, an option expiring after the ex date would take the dividend into account and would trade as if the stock were trading at 100. (Negative) interest rates may also lead to a similar effect. In the commodity world the cost of carry needs to be taken into account.
The question is always one of whether people think they can reliably predict that the option will be a good bet. The closer you get to its expiration, the easier it is to make that guess and the less risk there is. That may either increase or decrease the value of the option. This sometimes happens to me. It depends on how liquid the option is. Normally what I see happening is that the order book mutates itself around my order. I interpret this to mean that the order book is primarily market makers. They see a retail investor (me) come in and, since they don't have any interest in this illiquid option, they back off. Some other retail investor (or whatever) steps in with a market order, and we get matched up. I get a fill because I become the market maker for a brief while. On highly liquid options, buy limits at the bid tend to get swallowed because the market makers are working the spread. With very small orders (a contract or two) on very liquid options, I've had luck getting quick fills in the middle of the spread, which I attribute to MM's rebalancing their holdings on the cheap, although sometimes I like to think there's some other anal-retentive like me out there that hates to see such a lopsided book. :) I haven't noticed any particular tendency for this to happen more with puts or calls, or with buy vs sell transactions. For a while I had a suspicion that this was happening with strikes where IV didn't match IV of other strikes, but I never cared enough to chase it down as it was a minor part of my overall P/L. You can't know. It's not like every stock has options traded on it, so until you either see the options listed or a company announcement that option will trade on a certain date, there's no way to be sure. "Your broker likely didn't close your position out because it is a covered position. Why interfere with a trade that has no risk to it, from their perspective? There's no risk for the broker since your account holds the shares available for delivery (definition of covered), for if and when the options you wrote (sold) are exercised. And buyers of those options will eventually exercise the options (by expiration) if they remain in-the-money. There's only a chance that an option buyer exercises prematurely, and usually they don't because there's often time value left in the option. That the option buyer has an (ahem) ""option"" to exercise is a very key point.  You wrote: ""I fully expected my position to be automatically liquidated by whoever bought my call"". That's a false assumption about the way options actually work.  I suggest some study of the option exercise FAQs here: Perhaps if your position were uncovered – i.e. you wrote the call without owning the stock (don't try this at home, kids!) – and you also had insufficient margin to cover such a short position, then the broker might have justifiably liquidated your position. Whereas, in a covered call situation, there's really no reason for them to want to interfere – and I would consider that interference, as opposed to helpful.  The situation you've described is neither risky for them, nor out of the ordinary.  It is (and should be) completely up to you to decide how to close out the position. Anyway, your choices generally are:" Sounds like an illiquid option, if there are actually some bidders, market makers, then sell the option at market price (market sell order). If there are not market makers then place a really low limit sell order so that you can sit at the ask in the order book. A lot of time there is off-book liquidity, so there may be a party looking for buy liquidity. You can also exercise the option to book the loss (immediately selling the shares when they get delivered to you), if this is an American style option. But if the option is worthless then it is probably significantly underwater, and you'd end up losing a lot more as you'd buy the stock at the strike price but only be able to sell at its current market value. The loss could also be increased further if there are even MORE liquidity issues in the stock. "Your scenario depicts 2 ""in the money"" options, not ""at the money"". The former is when the share price is higher than the option strike, the second is when share price is right at strike. I agree this is a highly unlikely scenario, because everyone pricing options knows what everyone else in that stock is doing. Much about an option has everything to do with the remaining time to expiration. Depending on how much more the buyer believes the stock will go up before hitting the expiration date, that could make a big difference in which option they would buy. I agree with the others that if you're seeing this as ""real world"" then there must be something going on behind the scenes that someone else knows and you don't. I would tread with caution in such a situation and do my homework before making any move.   The other big factor that makes your question harder to answer more concisely is that you didn't tell us what the expiration dates on the options are. This makes a difference in how you evaluate them. We could probably be much more helpful to you if you could give us that information." "No.  The more legs you add onto your trade, the more commissions you will pay entering and exiting the trade and the more opportunity for slippage.  So lets head the other direction.   Can we make a simple, risk-free option trade, with as few legs as possible? The (not really) surprising answer is ""yes"", but there is no free lunch, as you will see.  According to financial theory any riskless position will earn the risk free rate, which right now is almost nothing, nada, 0%.   Let's test this out with a little example. In theory, a riskless position can be constructed from buying a stock, selling a call option, and buying a put option.  This combination should earn the risk free rate. Selling the call option means you get money now but agree to let someone else have the stock at an agreed contract price if the price goes up.  Buying the put option means you pay money now but can sell the stock to someone at a pre-agreed contract price if you want to do so, which would only be when the price declines below the contract price.  To start our risk free trade, buy Google stock, GOOG, at the Oct 3 Close:   495.52 x 100sh = $49,552 The example has 100 shares for compatibility with the options contracts which require 100 share blocks. we will sell a call and buy a put @ contract price of $500 for Jan 19,2013.   Therefore we will receive $50,000 for certain on Jan 19,2013, unless the options clearing system fails, because of say, global financial collapse, or war with Aztec spacecraft. According to google finance, if we had sold a call today at the close we would receive the bid, which is 89.00/share, or $8,900 total.  And if we had bought a put today at the close we would pay the ask, which is 91.90/share, or $9190 total. So, to receive $50,000 for certain on Jan 19,2013 we could pay $49,552 for the GOOG stock, minus $8,900 for the money we received selling the call option, plus a payment of $9190 for the put option we need to protect the value.  The total is $49,842.   If we pay $49,842 today, plus execute the option strategy shown, we would have $50,000 on Jan 19,2013.  This is a profit of $158, the options commissions are going to be around $20-$30, so in total the profit is around $120 after commissions.   On the other hand, ~$50,000 in a bank CD for 12 months at 1.1% will yield $550 in similarly risk-free interest.   Given that it is difficult to actually make these trades simultaneously, in practice, with the prices jumping all around, I would say if you really want a low risk option trade then a bank CD looks like the safer bet.  This isn't to say you can't find another combination of stock and contract price that does better than a bank CD -- but I doubt it will ever be better by very much and still difficult to monitor and align the trades in practice." How would this trade behave IRL? I don't know how the simulation handles limit orders and bid/ask spreads to know it's feasible, but buying at 4.04 when the current ask is 8.00 seems unlikely.  That would mean that all other sell orders between 8.00 and 4.04 were fulfilled, which means that there were very few sellers or that sell pressure spiked, both of which seem unlikely. In reality, it seems more likely that your order would have sat there until the ask dropped to $4.04 (if it ever did), and then you'd have to wait until the bid rose to $7.89 in order to sell them at that price. However, that kind of swing in option prices in not unrealistic.  Options near at-the-money tend to move in price at about 50% of the change in the underlying, so if amazon suddenly dropped by $5, the option price could drop by $2.60 (from 6.66 to $4.04), and then rise back to $7.89 if the price rose $8 (which would be 1% swing and not unheard of intra-day). But it sounds like you got very lucky (or the simulation doesn't handle option trading realistically) - I've traded options in the past and have had some breaks similar to yours.  I've also had bad breaks where I lost my entire investment (the options expire out-of-the money). So it should be a very limited part of your portfolio, and probably only used for risk management (e.g. buying put options to lock in some gains but keeping some upside potential). Depending on the day and even time, you'd get your $2 profit less the $5 commission. Jack's warning is correct, but more so for thinly traded options, either due to the options having little open interest or the stock not quite so popular. In your case you have a just-in-the-money strike for a highly traded stock near expiration. That makes for about the best liquidity one can ask for.  One warning is in order - Sometime friday afternoon, there will be a negative time premium. i.e. the bid might seem lower than in the money value. At exactly $110, why would I buy the option? Only if I can buy it, exercise, and sell the stock, all for a profit, even if just pennies. "I thought the other answers had some good aspect but also some things that might not be completely correct, so I'll take a shot. As noted by others, there are three different types of entities in your question:  The ETF SPY, the index SPX, and options contracts. First, let's deal with the options contracts.  You can buy options on the ETF SPY or marked to the index SPX.  Either way, options are about the price of the ETF / index at some future date, so the local min and max of the ""underlying"" symbol generally will not coincide with the min and max of the options.  Of course, the closer the expiration date on the option, the more closely the option price tracks its underlying directly.  Beyond the difference in how they are priced, the options market has different liquidity, and so it may not be able to track quick moves in the underlying. (Although there's a reasonably robust market for option on SPY and SPX specifically.) Second, let's ask what forces really make SPY and SPX move together as much as they do.  It's one thing to say ""SPY is tied to SPX,"" but how?  There are several answers to this, but I'll argue that the most important factor is that there's a notion of ""authorized participants"" who are players in the market who can ""create"" shares of SPY at will.  They do this by accumulating stock in the constituent companies and turning them into the market maker.  There's also the corresponding notion of ""redemption"" by which an authorized participant will turn in a share of SPY to get stock in the constituent companies. (See http://www.spdrsmobile.com/content/how-etfs-are-created-and-redeemed and http://www.etf.com/etf-education-center/7540-what-is-the-etf-creationredemption-mechanism.html) Meanwhile, SPX is just computed from the prices of the constituent companies, so it's got no market forces directly on it.  It just reflects what the prices of the companies in the index are doing. (Of course those companies are subject to market forces.) Key point: Creation / redemption is the real driver for keeping the price aligned.  If it gets too far out of line, then it creates an arbitrage opportunity for an authorized participant.  If the price of SPY gets ""too high"" compared to SPX (and therefore the constituent stocks), an authorized participant can simultaneously sell short SPY shares and buy the constituent companies' stocks.  They can then use the redemption process to close their position at no risk.  And vice versa if SPY gets ""too low."" Now that we understand why they move together, why don't they move together perfectly.  To some extent information about fees, slight differences in composition between SPY and SPX over time, etc. do play.  The bigger reasons are probably that (a) there are not a lot of authorized participants, (b) there are a relatively large number of companies represented in SPY, so there's some actual cost and risk involved in trying to quickly buy/sell the full set to capture the theoretical arbitrage that I described, and (c) redemption / creation units only come in pretty big blocks, which complicates the issues under point b. You asked about dividends, so let me comment briefly on that too.  The dividend on SPY is (more or less) passing on the dividends from the constituent companies. (I think - not completely sure - that the market maker deducts its fees from this cash, so it's not a direct pass through.)  But each company pays on its own schedule and SPY does not make a payment every time, so it's holding a corresponding amount of cash between its dividend payments.  This is factored into the price through the creation / redemption process.  I don't know how big of a factor it is though." Excellent, very sharp. No it will not be vega neutral exactly! If you think about it, what does a higher vol imply? That the delta of the option is higher than under BS model. Therefore, the vega should also be greater (simplistic explanation but generally accurate). So no, if you trade a 25-delta risky in equal size per leg, the vega will not be neutral. But, in reality, that is a very small portion of your risk. It plays a part, but in general the vanna position dominates by many many multiples.  What do you do that you asked such a question, if you don't mind? The answer is that the trader is hoping to profit from a potential rise in Implied volatility. He is isolating his exposure to IV only and mitigating his risk to the directional move of the underlying by hedging with the underlying. Basically, his delta is neutral. His gamma is positive and a potential source of profit, and his theta is negative which is a potential source of loss. He hopes that the profits from long gamma will overcome the loss from the short theta. he achieves this by actively gamma scalping to remain delta neutral over the life of the option. One broker told me that I have to simply read the ask size and the bid size, seeing what the market makers are offering. This implies that my order would have to match that price exactly, which is unfortunate because options contract spreads can be WIDE. Also, if my planned position size is larger than the best bid/best ask, then I should break up the order, which is also unfortunate because most brokers charge a lot for options orders. I know I can not trade futures realistically (I never claimed I could). All I wanted was some exposure to commodities.  If I could just trade many of these things in an ETF like GLD or XLV, I would have done that.   On the topic of margin, I appreciate your explaining that to me. I admit readily that I could never invest in futures straight, but I would like to get into commodities and other types of investments. I have tried to look for value in the market, but I have not found many things I would put my money in. I have gone as far as to look through OTC ADRs to find some foreign value, and I found nothing. I just want to be able to trade in any market, and I would consider shorting, but I don't like to be too risky. I want to go long on positions, and it seemed like commodities may be a good speculation to LOOK INTO. Taking rough rice as an example, there are millions (if not billions) of people who eat rice to survive. People will always need oil to fuel their cars. People will always need electricity. So I guess what I am trying to do is look into things that allow me to profit, regardless of where equities are going. The only thing I want to do is trade the options of the futures, not the actual futures themselves. I hope I did not confuse you. If I can earn even $20 from buying an option at a lower price and selling higher, it would allow me to have a greater breadth of tools to use when the market may be overvalued. This will work as intended, but there's another point to consider. In the US, the tax rate on proceeds from stock sales is higher for short term holdings, which are defined as held for less than one year. Both rates vary based on your income. Bracket numbers are for fiscal year 2014, filing as single. The difference between short and long term capital gains tax in the US is a minimum of ten percentage points, and works out to 15 percentage points on average. This is substantial. If you won't be reporting much income the year you move to the US (say because you only worked for a portion of the year) it is decidedly to your advantage to wait and sell the stocks in the US, to get that sweet 0% rate. At a minimum, you should hold the position for a year if you sell and rebuy, from a tax optimization perspective. Two caveats: