Can an ETF, open at a price other than what the pre-market was at?
If I understand you correctly, you are noticing that a stock's price can change drastically when the time changes from pre-market trading hours to open market hours. This could occur because a much smaller pool of investors make trades during pre-market and after-market hours. When the regular market opens there is a large influx of trades, causing the prices to jump. If you're talking about an ETF trading on Arca, it's probably because of the opening auction: The match price is the price that maximizes the volume that can be executed within the Auction Collars. The Core Open Auction will use the match price closest to the closing price of the previous trading day (based on normal market hours) if more than one indicative match price is valid. The core opening auction doesn't really take the opening session activity into account, as you can see - the market runs an auction and whatever price clears the most volume, within certain limits, is the opening print.
"And you have hit the nail on the head of holding gold as an alternative to liquid currency. There is simply no way to reliably buy and sell physical gold at the spot price unless you have millions of dollars. Exhibit A) The stock symbol GLD is an ETF backed by gold. Its shares are redeemable for gold if you have more than 100,000 shares then you can be assisted by an ""Authorized Participant"". Read the fund's details. Less than 100,000 shares? no physical gold for you. With GLD's share price being $155.55 this would mean you need to have over 15 million dollars, and be financially solvent enough to be willing to exchange the liquidity of shares and dollars for illiquid gold, that you wouldn't be able to sell at a fair price in smaller denominations. The ETF trades at a different price than the gold spot market, so you technically are dealing with a spread here too. Exhibit B) The futures market. Accepting delivery of a gold futures contract also requires that you get 1000 units of the underlying asset. This means 1000 gold bars which are currently $1,610.70 each. This means you would need $1,610,700 that you would be comfortable with exchanging for gold bars, which: In contrast, securitized gold (gold in an ETF, for instance) can be hedged very easily, and one can sell covered calls to negate transaction fees, hedge, and collect dividends from the fund. quickly recuperating any ""spread tax"" that you encounter from opening the position. Also, leverage: no bank would grant you a loan to buy 4 to 20 times more gold than you can actually afford, but in the stock market 4 - 20 times your account value on margin is possible and in the futures market 20 times is pretty normal (""initial margin and maintenance margin""), effectively bringing your access to the spot market for physical gold more so within reach. caveat emptor." Should do it through a limit auction book.   Management and shareholders pre ipo submit sealed limit sell orders. Buyers submit sealed limit buy orders, nobody can see where the price is going.  At 9AM, the price is calculated and whomever fills get filled and ta da everyone is trading at 9:30 when the market is open. "Generally, ETFs work on the basis that there exists a pair of values that can be taken at any moment in time: A Net Asset Value of each share in the fund and a trading market price of each share in the fund.  It may help to picture these in baskets of about 50,000 shares for the creation/redemption process. If the NAV is greater than the market price, then arbitrageurs will buy up shares at the market price and do an ""in-kind"" transaction that will be worth the NAV value that the arbitrageurs could turn around and sell for an immediate profit. If the market price is greater than the NAV, then the arbitrageurs will buy up the underlying securities that can be exchanged ""in-kind"" for shares in the fund that can then be sold on the market for an immediate profit. What is the ETF Creation/Redemption Mechanism? would be a source on this though I imagine there are others. Now, in the case of VXX, there is something to be said for how much trading is being done and what impact this can have. From a July 8, 2013 Yahoo Finance article: At big option trade in the iPath S&P 500 VIX Short-Term Futures Note   is looking for another jump in volatility.  More than 250,000 VXX options have already traded, twice its daily   average over the last month. optionMONSTER systems show that a trader   bought 13,298 August 26 calls for the ask price of $0.24 in volume   that was 6 times the strike's previous open interest, clearly   indicating new activity. Now the total returns of the ETF are a combination of changes in share price plus what happens with the distributions which could be held as cash or reinvested to purchase more shares." Firstly what are you trading that you could lose more than you put in? If you are simply trading stocks you will not lose more than you put in, unless you are trading on margin. A limit order is basically that, a limit on the maximum price you want your buy order bought at or the minimum price you want your sell order sold at. If you can't be glued to the screen all day when you place a limit order, and the market moves the opposite way, you may miss out on your order being executed. Even if you can be in front of the screen all day, you then have to decide if you want to chase the market of miss out on your purchase or sale. For example, if a stock is trading at $10.10 and you put a limit buy order to buy 1000 shares at or below $10.00 and the price keeps moving up to $10.20, then $10.30 and then $10.50, until it closes the day at $11.00. You then have the choice during the day to miss out on buying the shares or to increase your limit order in order to buy at a higher price. Sometime if the stock is not very liquid, i.e. it does not trade very often and has low volume, the price may hit $10.00 and you may only have part of your order executed, say 500 out of your 1000 shares were bought. This may mean that you may have to increase the price of your remaining order or be happy with only buying 500 shares instead of 1000. The same can happen when you are selling (but in reverse obviously). With market order, however, you are placing a buy order to buy at the next bid price in the depth or a sell order to sell at the next offer price in the depth. See the market depth table below:  Note that this price depth table is taken before market open so it seems that the stock is somewhat illiquid with a large gap between the first and second prices in the buyers (bid) prices. When the market opened this gap is closed, as WBC is a major Australian bank and is quite liquid. (the table is for demonstration purposes only). If we pretend that the market was currently open and saw the current market depth for WBC as above, you could decide to place a limit sell order to sell 1000 shares at say $29.91. You would sell 100 shares straight away but your remaining 900 sell order will remain at the top of the Sellers list. If other Buyers come in at $29.91 you may get your whole sale completed, however, if no other Buyers place orders above $29.80 and other Sellers come into the market with sell orders below $29.91, your remaining order may never be executed. If instead you placed a market sell order you would immediately sell 100 shares at $29.91 and the remaining 900 shares at $29.80. (so you would be $99 or just over 0.3% worse off than if you were able to sell the full 1000 shares at $29.91). The question is how low would you have had to lower your limit order price if the price for WBC kept on falling and you had to sell that day? There are risks with whichever type of order you use. You need to determine what the purpose of your order is. Is it to get in or out of the market as soon as possible with the possibility of giving a little bit back to the market? Or is it to get the price you want no matter how long it takes you? That is you are willing to miss out on buying the shares (can miss out on a good buy if the price keeps rising for weeks or months or even years) or you are willing to miss out on selling them right now and can wait for the price to come back up to the price you were willing to sell at (where you may miss out on selling the shares at a good price and they keep on falling and you give back all your profits and more). Just before the onset of the GFC I sold some shares (which I had bought a few years earlier at $3.40) through a market order for $5.96. It had traded just above $6 a few days earlier, but if instead of a market order I had placed a limit order to sell at $6.00 or more I would have missed out on the sale. The price never went back up  to $6 or above, and the following week it started dropping very quickly. It is now trading at about $1.30 and has never gone back above $2.00 (5.5 years later). So to me placing a limit order in this case was very risky. The key two things to consider when looking at similar/identical ETFs is the typical (or 'indicative') spread, and the trading volume and size of the ETF. Just like regular stocks, thinly traded ETF's often have quite large spreads between buy and sell: in the 1.5-2%+ range in some cases. This is a huge drain if you make a lot of transactions and can easily be a much larger concern than a relatively trivial difference in ongoing charges depending on your exact expected trading frequency. Poor spreads are also generally related to a lack of liquidity, and illiquid assets are usually the first to become heavily disconnected from the underlying in cases where the authorized participants (APs) face issues. In general with stock ETFs that trade very liquid markets this has historically not been much of an issue, as the creation/redemption mechanism on these types of assets is pretty robust: it's consequences on typical spread is much more important for the average retail investor. On point #3, no, this would create an arbitrage which an authorized participant would quickly take advantage of. Worth reading up about the creation and redemption mechanism (here is a good place to start) to understand the exact way this happens in ETFs as it's very key to how they work. Your order may or may not be executed.  The price of stock can open anywhere.  Often yesterday's close is a good indication of today's open, but with a big event overnight, the open may be somewhere quite different.  You'll have to wait and see like the rest of us.  Also, even if it doesn't execute at the open, the price could vary during the day and it might execute later. "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." Sounds to me like you're describing just how it should work.  Ask is at 30, Bid is at 20; you offer a new bid at 25.  Either: Depending on liquidity, one or the other may be more likely. This Investorplace article on the subject describes what you're seeing, and recommends the strategy you're describing precisely. Instead of a market order, take advantage of the fact that the options world truly is a marketplace — one where you can possibly get a better price just by asking. How does that work? If you use a limit order (instead of a market order) when opening a position, you can tell your broker how much you are willing to pay to enter a trade. For example, if you enter a limit price of $1.15, you can see whether the market-maker will bite. You will be surprised at how many times you will get your price (i.e., $1.15) instead of the ask price of $1.30. If your order at $1.15 is not filled after a few minutes, you can modify your order and pay the ask price by entering a market order or limit order at the ask price (that is, you can tell your broker to pay no more than $1.30).