Bid-Ask at market open, which comes first? [duplicate]
"When you place a limit sell order of $10.00 (for a stock on an option) you are adding your order to the book.  Anyone who places a buy at-the-market or with a limit price over $10.00 will have that order immediately fulfilled through the offer you have placed on the book. On the other hand, if that other person places a buy for $8.00, then the spread will now be ""$8.00 bid, $10.00 ask"". Priority is based on first the price (all $9.99 asks will clear before $10.00) and within each bucket this is based on the time your order was submitted. This is why in bidding markets (including eBay) buying at $x.01 is way better than $x.00 and selling at $x.99 is better than $(x+1).00. Source: https://en.wikipedia.org/wiki/Order_(exchange) under ""first-come-first-served""" The options market requires much more attention to avoid the situation you're describing. An overnight $10 ask will remain on the books most likely as Good-Til-Canceled.  The first to bid the low order gets it.  If traders are paying attention, which they probably are then they will bid at $10.  If not, they will bid immediately at $20. If they crossed the order, it would be filled at their higher than $10 bid. This is all governed by the exchange where the ask is posted, and most implement price-time priority.
Rule 610 (Google for it) stands that if Bid and Ask are the same, the market is considered Locked, and the exchange must stop all trading. So the same person can't quote the same bid and ask price. However, HFTs have found ways to circumvent this limitation when exchanges created special order types for them, e.g. Spam-and-Cancel "Assuming you are executing your order on a registered exchange by a registered broker, your order will be filled at the best bid price available.  This is because brokers are legally obliged to get the best price available. For example, if the market is showing a bid of 49.99 and an offer of 50.01 and you submit an order to offer 1000 shares at 5.00, your order will be filled at 49.99.  This is assuming the existing bids are for enough shares to fill all of the 1000 shares being offered.  If the share you are offering lacks the necessary liquidity to fill the order - i.e., the 49.99 bid is for less than 1000 shares and the ""level two"" bids are not enough to fill the remaining shares, then the order would be posted in the market as an offer to sell the balance (1000 - shares filled at 49.99 and those filled at level two bids) at 5.00.   I'm pretty sure that the scenario you are describing would be described as market manipulation and it would be against the law." In terms of pricing the asset, this functions in exactly the same way as a regular sell, so bids will have to be hit to fill the trade. When shorting an equity, currency is not borrowed; the equity is, so the value of per share liability is equal to it's last traded price or the ask if the equity is illiquid. Thus when opening a short position, the asks offer nothing to the process except competition for your order getting filled. Part of managing the trade is the interest rate risk.  If the asks are as illiquid as detailed in the question, it may be difficult even to locate the shares for borrowing. As a general rule, only illiquid  equities or those in free fall may be temporarily unable for shorting. Interactive Brokers posts their securities financing availabilities and could be used as a proxy guide for your broker. It does sometimes open one day the same as it closed the previous day.  Take a look at ESCA, it closed October 29th at 4.50, at opened November 1st at 4.50.  It's more likely to change prices overnight than it is between two successive ticks during the day, because a lot more time passes, in which news can come out, and in which people can reevaluate the stock. The best ask is the lowest ask, and the best bid is the highest bid.  If the ask was lower than the bid then they crossed, and that would be a crossed market and quickly resolved. So the bid will almost always be cheaper than the ask. A heuristic is that a bid is the revenue of the stock at any given time while the ask is the cost, so the market will only ever offer a profit to itself not to the liquidity seeker. If examining the book vertically, all orders are usually sorted descending. Since the best ask is the lowest ask, it is on the bottom of the asks, and vice versa for the best bid. The best bid & best ask will be those closest since that's the narrowest spread and price-time priority will promise that a bid that crosses the asks will hit the lowest ask, the best possible price for the bidder and vice versa for an ask that crosses the best bid. The offering price is the price at which that IPO is, well, offered. Think of it as a suggested retail price. The opening price is the actual price at which trading begins, on a particular day, for a stock. That price depends on demand/overnight-orders/what-have-you. Think of this as the actual price in the store. I think that if the price does not go very far up, then your order will open on 101, because you are setting a limit order, if suddenly the price goes up very quickly or with a gep even, then you may not be given a position. But this is with a limit order and it is better to check with the broker. There are also warrants in which you can adjust the price range, for example, from 101 to 103, and at a sharp price jump, it is possible for you and would not give a position at a price of 101, but perhaps 103 would get. The one whose order gets to the exchange first. The exchange receives the orders and arranges them in First-In-First-Out order, by which they're then executed. At some point it is synchronized and put into a list. Whoever gets to that point first - gets the deal. "- 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" "I can think of the following situations in which one could see a trade occur between the visible best bid & offer: 1) on a public exchange, people have posted hidden limit orders with either bid prices above the best visible bid or offers below the best visible offer, and incoming orders have executed against this hidden liquidity[1]; 2) some orders may have been matched in dark pools which offer ""mid-point matching"" where buy and sell orders are matched using the mid-point of the best available publicly posted bid and offer as the reference price, and which executed trades are then reported to the public markets; or 3) some internalising broker has traded off exchange directly with a client and is now reporting the trade to the public as is often required. Now how exactly any of the above situations indicates that a ""trend is about to come to an end"", I do not know. [1] Exchanges often match orders on a price/visibility/time basis, whereby the orders are prioritised by price (better prices get to trade first), then by visibility (visible orders get to trade first) then by time (first come, first serve)." It depends on the sequence in which the order [bid and ask] were placed. Please read the below question to understand how the order are matched. How do exchanges match limit orders? Because in the case for 100/101, if you wanted to placed a limit buy order at top of the bid list you would place it at 101 and get filled straight away. If placing a limit buy order at the top of 91 (for 90/98) you would not get filled but just be placed at the top of the list. You might get filled at a lower price if an ask comes in matching your bid, however you might never get filled. In regards to market orders, with the 100/101 being more liquid, if your market order is larger than the orders at 101, then the remainder of your order should still get filled at only a slightly higher price. In regards to market orders with the 90/98, being less liquid, it is likely that only part of your order gets filled, and any remained either doesn't get filled or gets filled at a much higher price. "Well, they don't have to enter a market order. I was just saying that for your benefit.   In practice what will really happen is they'll say to themselves   ""I want ABC for no more than 70.00""  The current bid is at 69.60 They'll use a limit order on 10,000 shares. If anyone offers them more than 70.00 the computer program they're using will not accept.  However, the shares won't be bought all at once. A limit order for 10,000 shares will be spit into 1,000 shares at 69.70 and 10,000 for 69.65  The HFT can then make a reasonable guess someone is buying in bulk. So then the HFT sends out a sell order saying ""10 shares at 70.10"". The guy doesn't want that so they do it over again at 70.09  Eventually they notice when the guy accepts at 70.00  So now they knew this guy is willing to pay that. Then HFT buys all the shares they can. ALL SHARES, not just the amount the guy wants. They buy it all at 69.95, which is higher than the 69.70 the guy just paid or whatever.  They then sell it all back to the guy at 70.00  The guy has no choice because all the shares are now gone. He has to pay his highest price.   Once the guy gets his order the HFT just dumps the rest of the shares back at the price they bought them at.  edit: Another way to pull this off is to just literally build your own exchange. Then you can do all of this without any clever tricks. You can just outright give yourself preference over everyone else because you can truly decide what order the trades are being executed." thanks.  I have real time quotes, but in the contest, if you put in a market order the trade might happen at the delayed quote price and not the real time price.  Does anyone know at which price it will trade, delayed or real time? "This is a misconception. One of the explanations is that if you buy at the ask price and want   to sell it right away, you can only sell at the bid price. This is incorrect. There are no two separate bid and ask prices. The price you buy (your ""bid"") is the same price someone else sells (their ""sell""). The same goes when you sell - the price you sell at is the price someone else buys. There's no spread with stocks. Emphasized it on purpose, because many people (especially those who gamble on stock exchange without knowing what they're doing) don't understand how the stock market works. On the stock exchange, the transaction price is the match between the bid price and the ask price. Thus, on any given transaction, bid always equals ask. There's no spread. There is spread with commodities (if you buy it directly, especially), contracts, mutual funds and other kinds of brokered transactions that go through a third party. The difference (spread) is that third party's fee for assuming part of the risk in the transaction, and is indeed added to your cost (indirectly, in the way you described). These transactions don't go directly between a seller and a buyer. For example, there's no buyer when you redeem some of your mutual fund - the fund pays you money. So the fund assumes certain risk, which is why there's a spread in the prices to invest and to redeem. Similarly with commodities: when you buy a gold bar - you buy it from a dealer, who needs to keep a stock. Thus, the dealer will not buy from you at the same price: there's a premium on sale and a discount on buy, which is a spread, to compensate the dealer for the risk of keeping a stock."