Why bid and ask do not match the price at which the stock is being traded [duplicate]
"Assuming that no one else has hit the ask, and the asks are still there, yes, you will fill $54.55 as long as you didn't exhaust that ask. Actually, there is no ""current price at which the stock is exchanging hands""; in reality, it is ""the last price traded"". The somebody who negotiated prices between buyers & sellers is the exchange through their handling of bids & asks.  The real negotiation comes between bids & asks, and if they meet or cross, a trade occurs. It's not that both bid & ask should be $54.55, it's that they were. To answer the title, the reasons why the bid and ask (even their midpoint) move away from the last price are largely unknown, but at least for the market makers, if their sell inventory is going away (people are buying heavily and they're running out of inventory) they will start to hike up their asks a lot and their bids a little because market makers try to stay market neutral, having no opinion on whether an asset will rise or fall, so with stocks, that means having a balanced inventory of longs & shorts.  They want to (sometimes have to depending on the exchange) accommodate the buying pressure, but they don't want to lose money, so they simply raise the ask and then raise the bid as people hit their asks since their average cost basis has risen. In fact (yahoo finance is great about showing this), there's rarely 1 bid and 1 ask.  Take a look at BAC's limit book: http://finance.yahoo.com/q/ecn?s=BAC+Order+Book You can see that there are many bids and many asks.  If one ask is exhausted, the next in line is now the highest.  The market maker who just sold at X will certainly step over the highest bid to bid at X*0.9 to get an 11% return on investment."
"You need to hope that a fund exists targeting the particular market segment you are interested in. For example, searching for ""cloud computing ETF"" throws up one result. You'd then need to read all the details of how it invests to figure out if that really matches up with what you want - there'll always be various trade-offs the fund manager has to make. For example, with this fund, one warning is that this ETF makes allocations to larger firms that are involved in the   cloud computing space but derive the majority of their revenues from   other operations Bear in mind that today's stock prices might have already priced in a lot of future growth in the sector. So you might only make money if the sector exceeds that predicted growth level (and vice versa, if it grows, but not that fast, you could lose money). If the sector grows exactly as predicted, stock prices might stay flat, though you'd still make a bit of money if they pay dividends. Also, note that the expense ratios for specialist funds like this are often quite a bit higher than for ""general market"" funds. They are also likely to be traded less frequently, which will increase the ""bid-ask"" spread - i.e. the cost of buying into and getting out of these funds will be higher." Imagine you have a bank account with $100 in it. You are thinking about selling this bank account, so ask for some bids on what it's worth. You get quotes of around $100. You decide to sell it, but before you do, you take $50 out of it to have in cash. Would you expect the market to still pay $100 for the account? The dividend is effectively the cash being withdrawn. The stock had on account a large amount of cash (which was factored into it's share price), it moved that cash out of it's account (to its shareholders), and as a result the stock instantly becomes priced lower as this cash is no longer part of it, just as it is in the bank account example. "As I understand it, Implied Volatility represents the expected gyrations of an options contract over it's lifetime.  No, it represents that expected movement of the underlying stock, not the option itself.  Yes, the value of the option will move roughly in the same direction the value of the stock, but that's not what IV is measuring. I even tried staring at the math behind the Options pricing model to see if that could make more sense for me but that didn't help. That formula is correct for the Black-Scholes model - and it is not possible (or at least no one has done it yet) to solve for s to create a closed-form equation for implied volatility.  What most systems do to calculate implied volatility is plug in different values of s (standard deviation) until a value for the option is found that matches the quoted market value ($12.00 in this example).  That's why it's called ""implied"" volatility - the value is implied from market prices, not calculated directly. The thing that sticks out to me is that the ""last"" quoted price of $12 is outside of the bid-ask spread of $9.20 to $10.40, which tells me that the underlying stock has dropped significantly since the last actual trade.   If the Implied Vol is calculated based on the last executed trade, then whatever algorithm they used to solve for a volatility that match that price couldn't find a solution, which then choose to show as a 0% volatility.   In reality, the volatility is somewhere between the two neighbors of 56% and 97%, but with such a short time until expiry, there should be very little chance of the stock dropping below $27.50, and the value of the option should be somewhere around its intrinsic value (strike - stock price) of $9.18." "- In a quote driven market, must every investor trade with a market        maker? In other words, two parties that are both not market makers        cannot trade between themselves directly? In a way yes, all trades go through a market maker but those trades can be orders put in place by a ""person"" IE: you, or me. - Does a quote driven market only display the ""best"" bid and ask        prices proposed by the market makers? In other words, only the        highest bid price among all the market makers is displayed, and        other lower bid prices by other market makers are not? Similarly,        only the lowest ask price over all market makers is displayed, and        other higher ask prices by other market makers are not? No, you can see other lower bid and higher ask prices. - In a order-driven market, is it meaningful to talk about ""the current stock price"", which is the price of last transaction? Well that's kind of an opinion. Information is information so it won't be bad to know it. Personally I would say the bid and ask price is more important. However in the real world these prices are changing constantly and quickly so realistically it is easier to keep track of the quote price and most likely the bid/ask spread is small and the quote will fall in between. The less liquid a security is the more important the bid/ask is. -- This goes for all market types. - For a specific asset, will there be several transactions happened at    the same time but with different prices? Today with electronic markets, trades can happen so quickly it's difficult to say. In the US stock market trades happen one at a time but there is no set time limit between each trade. So within 1 second you can have a trade be $50 or $50.04. However it will only go to $50.04 when the lower ask prices have been exhausted.   - Does an order driven market have market makers?  By definition, no. - What are some examples of quote driven and order driven financial markets, in which investors are commonly trading stocks and derivatives, especially in U.S.? Quote driven market: Bond market, Forex. Order driven market: NYSE comes from an order driven market but now would be better classified as a ""hybird market"" Conclusion: If you are asking in order to better understand today's stock markets then these old definitions of Quote market or Order market may not work. The big markets in the real world are neither. (IE: Nasdaq, NYSE...) The NYSE and Nasdaq are better classified as a ""hybird market"" as they use more then a single tactic from both market types to insure market liquidity, and transparency. Markets these days are strongly electronic, fast, and fairly liquid in most cases. Here are some resources to better understand these markets: An Introduction To Securities Markets The NYSE And Nasdaq: How They Work Understanding Order Execution" One difference is the bid/ask spread will cost you more in a lower cost stock than a higher cost one. Say you have two highly liquid stocks with tiny spreads: If you wanted to buy say $2,000 of stock: Now imagine these are almost identical ETFs tracking the S&P 500 index and extrapolate this to a trade of $2,000,000 and you can see there's some cost savings in the higher priced stock. As a practical example, recently a popular S&P 500 ETF (Vanguard's VOO) did a reverse split to help investors minimize this oft-missed cost. "I think the first misconception to clear up is that you are implying the price of a stock is set by a specific person. It is not. The price of a stock is equal to the value that someone most recently traded at. If Apple last traded at $100/share, then Apple shares are worth $100. If good news about Apple hits the market and people holding the shares ask for more money, and the most recent trade becomes $105, then that is now what Apple shares are worth. Remember that generally speaking, the company itself does not sell you its shares - instead, some other investor sells you shares they already own. When a company sells you shares, it is called a 'public offering'. To get to your actual question, saying something is 'priced in' implies that the 'market' (that is, investors who are buying and selling shares in the company) has already considered the impacts of that something. For example, if you open up your newspaper and read an article about IBM inventing a new type of computer chip, you might want to invest in IBM. But, the rest of the market has also heard the news. So everyone else has already traded IBM assuming that this new chip would be made. That means when you buy, even if sales later go up because of the new chip, those sales were already considered by the person who chose the price to sell you the shares at. One principle of the stock market (not agreed to by all) is called market efficiency. Generally, if there were perfect market efficiency, then every piece of public information about a company would be perfectly integrated into its stock price. In such a scenario, the only way to get real value when buying a company would be to have secret information of some sort. It would mean that everyone's collective best-guess about what will happen to the company has been ""priced-in"" to the most recent share trade." A stock is only worth what someone is willing to pay for it. If it trades different values on different days, that means someone was willing to pay a higher price OR someone was willing to sell at a lower price.  There is no rule to prevent a stock from trading at $10 and then $100 the very next trade... or $1 the very next trade. (Though exchanges or regulators may halt trading, cancel trades, or impose limits on large price movements as they deem necessary, but this is beside the point I'm trying to illustrate). Asking what happens from the close of one day to the open of the next is like asking what happens from one trade to the next trade... someone simply decided to sell or pay a different price.  Nothing needs to have happened in between. "What if everyone decided to sell all the shares at a given moment, let's say when the stock is trading at $40? It would fall to the lowest bid price, which could be $0.01 if someone had that bid in place. Here is an example which I happened to find online:  Notice there are orders to buy at half the market price and lower... probably all the way down to pennies.  If there were enough selling activity to fill all of those bids you see, then the market price would be the lowest bid on the screen.  Alternatively, the bid orders could be pulled (cancelled), which would also let the price free-fall to the lowest bid even if there were few actual sellers. Bid-stuffing is what HFT (high frequency trading) algorithms sometimes do, which some say caused the Flash Crash of May 2010.  The computers ""stuff"" bids into the order book, making it look like there is demand in order to trigger a market reaction, then they pull the bids to make the market fall.  This sort of thing happens all the time and Nanex documents it http://www.nanex.net/FlashCrash/OngoingResearch.html Quote stuffing defined: http://www.investopedia.com/terms/q/quote-stuffing.asp I remember the day of the Flash Crash very well.  I found this video on youtube of CNBC at that time.  Watch from the 5:00 min mark on the video as Jim Crammer talks about PG easily not being worth the price of the market at that time.  He said ""Who cares?"", ""Its not a real price"", ""$49.25 bid for 50,000 shares if I were at my hedge fund.""  http://www.youtube.com/watch?v=86g4_w4j3jU You can value a stock how you want, but its only actually worth what someone will give you for it. More examples: Anadarko Petroleum, which as we noted in today's EOD post, lost $45 billion in market cap in 45 milliseconds (a collapse rate of $1 billion per millisecond), flash crashing from $90 all the way to an (allegedly illegal) stub quote of $0.01. http://www.zerohedge.com/news/2013-05-17/how-last-second-flash-crash-pushed-sp-500-1667-1666 How 10,000 Contracts Crashed The Market: A Visual Deconstruction Of Last Night's E-Mini Flash Crash http://www.zerohedge.com/news/2012-12-21/how-10000-contracts-crashed-market-visual-deconstruction-last-nights-e-mini-flash-cr Symantec Flash-Crash Destroys Over $1.5 Billion In Less Than A Second http://www.zerohedge.com/news/2013-04-30/symantec-flash-crash-destroys-over-15-billion-less-second This sort of thing happens so often, I don't pay much attention anymore."