Options liquidity and trading positions larger than the daily volume?
You definitely cannot be guaranteed to get the bid or ask if you are selling more than are available/desired at those prices. What prices you do get depends on who is watching that contract and how willing they are to trade with you. This question is not much different from the question of whether you can easily get into or out of a large position in an illiquid small stock easily.  You can get out quickly if you are willing to take pennies on the dollar, or you may get a reasonable price if you take a long time to get out of (or into) your position.  You can't normally do both. In general taking large positions in illiquid assets is not something people want to do without lining up a buyer/seller beforehand.  Instead see if you can achieve your objective with liquid investments. 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'm assuming the question is about how to compare two ETFs that track the same index. I'd look at (for ETFs -- ignoring index funds): So, for example you might compare SPY vs IVV: SPY has about 100x the volume. Sure, IVV has 2M shares trading, so it is liquid ""enough"". But the bigger volume on SPY might matter to you if you use options: open interest is as much as 1000x more on SPY. Even if you have no interest in options, the spreads on SPY are probably going to be slightly smaller. They both have 0.09% expense ratios. When I looked on 2010-9-6, SPY was trading at a slight discount, IVV was at a slight premium. Looking for any sort of trend is left as an exercise to the reader... Grab the prospectus for each to examine the rules they set for fund makeup. Both come from well-known issuers and have a decent history. (Rather than crazy Uncle Ed's pawn shop, or the Central Bank of Stilumunistan.) So unless you find something in the SPY prospectus that makes you queasy, the higher volume and equal expense ratios would seem to suggest it over IVV. The fact that it is at a (tiny) discount right now is a (tiny) bonus." "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:" "For stock options, where I'm used to seeing these terms: Volume is usually reported per day, whereas open interest is cumulative. In addition, some volume closes positions and some opens positions.  For example, if I am long one contract and sell it to someone who was short one contract, then that adds to volume and reduces open interest.  If I hold no contracts and sell (creating a short position) to someone who also had no contracts, then I add to volume and I increase open interest. EDIT: With the clarification in your comment, then I would say some people opened and closed positions in that one day.  Their opening and closing trades both contribute to ""volume"" but they have not net position in the ""open interest.""" "In essence the problem that the OP identified is not that the FX market itself has poor liquidity but that retail FX brokerage sometimes have poor counterparty risk management. The problem is the actual business model that many FX brokerages have. Most FX brokerages are themselves customers of much larger money center banks that are very well capitalized and provide ample liquidity. By liquidity I mean  the ability to put on a position of relatively decent size (long EURUSD say) at any particular time with a small price impact relative to where it is trading. For spot FX, intraday bid/ask spreads are extremely small, on the order of fractions of pips for majors (EUR/USD/GBP/JPY/CHF). Even in extremely volatile situations it rarely becomes much larger than a few pips for positions of 1 to 10 Million USD equivalent notional value in the institutional market. Given that retail traders rarely trade that large a position, the FX spot market is essentially very liquid in that respect. The problem is that there are retail brokerages whose business model is to encourage excessive trading in the hopes of capturing that spread, but not guaranteeing that it has enough capital to always meet all client obligations. What does get retail traders in trouble is that most are unaware that they are not actually trading on an exchange like with stocks. Every bid and ask they see on the screen the moment they execute a trade is done against that FX brokerage, and not some other trader in a transparent central limit order book. This has some deep implications. One is the nifty attribute that you rarely pay ""commission"" to do FX trades unlike in stock trading. Why? Because they build that cost into the quotes they give you. In sleepy markets, buyers and sellers cancel out, they just ""capture"" that spread which is the desired outcome when that business model functions well.  There are two situations where the brokerage's might lose money and capital becomes very important. In extremely volatile markets, every one of their clients may want to sell for some reason, this forces the FX brokers to accumulate a large position in the opposite side that they have to offload. They will trade in the institutional market with other brokerages to net out their positions so that they are as close to flat as possible. In the process, since bid/ask spreads in the institutional market is tighter than within their own brokerage by design, they should still make money while not taking much risk. However, if they are not fast enough, or if they do not have enough capital, the brokerage's position might move against them too quickly which may cause them lose all their capital and go belly up. The brokerage is net flat, but there are huge offsetting positions amongst its clients. In the example of the Swiss Franc revaluation in early 2015, a sudden pop of 10-20% would have effectively meant that money in client accounts that were on the wrong side of the trade could not cover those on the other side. When this happens, it is theoretically the brokerage's job to close out these positions before it wipes out the value of the client accounts, however it would have been impossible to do so since there were no prices in between the instantaneous pop in which the brokerage could have terminated their client's losing positions, and offload the risk in the institutional market. Since it's extremely hard to ask for more money than exist in the client accounts, those with strong capital positions simply ate the loss (such as Oanda), those that fared worse went belly up. The irony here is that the more leverage the brokerage gave to their clients, the less money would have been available to cover losses in such an event. Using an example to illustrate: say client A is long 1 contract at $100 and client B is short 1 contract at $100. The brokerage is thus net flat. If the brokerage had given 10:1 leverage, then there would be $10 in each client's account. Now instantaneously market moves down $10. Client A loses $10 and client B is up $10. Brokerage simply closes client A's position, gives $10 to client B. The brokerage is still long against client B however, so now it has to go into the institutional market to be short 1 contract at $90. The brokerage again is net flat, and no money actually goes in or out of the firm. Had the brokerage given 50:1 leverage however, client A only has $2 in the account. This would cause the brokerage close client A's position. The brokerage is still long against client B, but has only $2 and would have to ""eat the loss"" for $8 to honor client B's position, and if it could not do that, then it technically became insolvent since it owes more money to its clients than it has in assets. This is exactly the reason there have been regulations in the US to limit the amount of leverage FX brokerages are allowed to offer to clients, to assure the brokerage has enough capital to pay what is owed to clients." That's not 100% correct, as some leveraged vehicles choose to re-balance on a monthly basis making them less risky (but still risky).  If I'm not mistaken the former oil ETN 'DXO' was a monthly re-balance before it was shut down by the 'man' Monthly leveraged vehicles will still suffer slippage, not saying they won't.  But instead of re-balancing 250 times per year, they do it 12 times.   In my book less iterations equals less decay. Basically you'll bleed, just not as much.  I'd only swing trade something like this in a retirement account where I'd be prohibited from trading options. Seems like you can get higher leverage with less risk trading options, plus if you traded LEAPS, you could choose to re-balance only once per year. I just called options express, and apparently you need a margin account for futures and options, but you don't NEED margin to trade futures. I will have to debate the merits, but I think I may try playing with it once I build up my regular stock account. So, this isn't always the case, but in the example provided the option is most likely in the money or near the money since the delta is nearly 1 - indicating that a $1 move in the underlying results in a $0.92 move in the option - this will happen when the expiration is very far out or the option is in the money. As expiration gets closer, movements in the underlying become more pronounced in the options because the probability of the stock price moving from its current position is lower.    As the probability of the stock price moving goes down, the delta of in the money options approaches 100, eventually reaching 100 at expiration. Another way to word this is that the premium on in the money options shrinks as expiration approaches and the intrinsic value of the option increases as percentage of total value so that movements in the underlying stock price become a greater influence on the option price - hence a greater delta. Again, if the option is out of the money, this is not the case. "I'm not sure which article you are referring to- if you are talking about the convergex article.... it literally describes what they did in the article.   Tradeworx and software company thesys(both founded by manoj narang) provide data to the sec and function as market makes- they are highly respected and handle over 5% of us equity by volume.   Their ""head people"" is manoj narang. I don't think he ""bailed out"". As you can read [here](https://research-doc.credit-suisse.com/docView?sourceid=em&amp;document_id=x569866&amp;serialid=lZPbU6l0cgAqB%2B1gg4uZFLk14dBwhfSb9lZ3%2BdmPHV4%3D) they are willing 53% of the trades they place everyday and have   He has stated in an interview he wants to explore options trading.   They were debunking myths because of the regulators wanted answers and at the time hft was not understood very well. Narang also testified at a senate committee[video here](https://youtu.be/NG47K41Q7KA)"