Market Close Order
"During the day, market and limit orders are submitted at any time by market participants and there is a bid and an ask that move around over time.  Trades occur whenever a market order is submitted or a limit order is submitted that at a price that matches or exceeds an existing limit order.  If you submit a market order, it may consume all best-price limit orders and you can get multiple prices, changing the bid or ask at the same time.  All that stuff happens during the trading day only. What happens at the end of the day is different.  A bunch of orders that were submitted during the day but marked as ""on close"" are aggregated with any outstanding limit orders to create a single closing price according to the algorithm established by the exchange.  Each exchange may handle the details of this closing event differently.  For example, the Nasdaq's closing cross or the NYSE's closing auction. The close is the most liquid time of the day, so investors who are trading large amounts and not interested in intraday swings will often submit a market-on-close or limit-on-close order.  This minimizes their chance of affecting the price or crossing a big spread.  It's actually most relevant for smaller stocks, which may have too little volume during the day to make big trades, but have plenty at the close.  In short, the volume you see is due to these on-close orders. The spike in volume most likely has no special information about what will happen overnight or the next day.  It's probably just a normal part of the market for illiquid stocks."
A stop-loss order becomes a market order when a trade has occurred at or below the trigger price you set when creating the order. This means that you could possibly end up selling some or all of your position at a price lower than your trigger price. For relatively illiquid securities your order may be split into transactions with several buyers at different prices and you could see a significant drop in price between the first part of the order and the last few shares. To mitigate this, brokers also offer a stop-limit order, where you set not only a trigger price, but also a minimum price that you are will to accept for your shares. This reduces the risk of selling at rock bottom prices, especially if you are selling a very large position. However, in the case of a flash crash where other sellers are driving the price below your limit, that part of your order may never execute and you could end up being stuck with a whole lot of shares that are worth less than both your stop loss trigger and limit price. For securities that are liquid and not very volatile, either option is a pretty safe way to cut your losses. For securities that are illiquid and/or very volatile a stop-limit order will prevent you from cashing out at bottom dollar and giving away a bargain to lurkers hanging out at the bottom of the market, but you may end up stuck with shares you don't want for longer than originally planned. It's up to you to decide which kind of risk you prefer. It depends on how you place your stop order and the type of stop orders available from your broker. If you place a stop market order and the following day the stock opens below your stop your stock will be stopped out at or around the opening price, meaning you can potentially end up with quite a large gap. If you place a stop limit order, say you place your stop at $10.00 with a limit price of $9.90, and if the price opens below $9.90, say at $9.50, your limit sell order of $9.90 will be placed onto the market but it will not be executed until the price goes back up to $9.90 or above. The third option is to place a Guaranteed Stop Loss, and as specified you are guaranteed your stop price even if the price gaps down below your stop price. You will be paying an extra fee for the Guaranteed Stop Loss Order, and they are usually mainly available with CFD Brokers (so if you are in the USA you might be out of luck). "My broker offers the following types of sell orders: I have a strategy to sell-half of my position once the accrued value has doubled.  I take into account market price, dividends, and taxes (Both LTgain and taxes on dividends).  Once the market price exceeds the magic trigger price by 10%, I enter a ""trailing stop %"" order at 10%.  Ideally what happens is that the stock keeps going up, and the trailing stop % keeps following it, and that goes on long enough that accrued dividends end up paying for the stock.  What happens in reality is that the stock goes up some, goes down some, then the order gets cancelled because the company announces dividends or something dumb like that. THEN I get into trouble trying to figure out how to re-enter the order, maintaining the unrealized gain in the history of the trailing stop order.  I screwed up and entered the wrong type of order once and sold stock I didn't want to. Lets look at an example. a number of years ago, I bought some JNJ -- a hundred shares at 62.18.  - Accumulated dividends are 2127.75  - My spreadsheet tells me the ""double price"" is 104.54, and double + 10% is 116.16.  - So a while ago, JNJ exceeded 118.23, and I entered a Trailing Stop 10% order to sell 50 shares of JNJ.  The activation price was 106.41.  - since then, the price has gone up and down...  it reached a high of 126.07, setting the activation price at 113.45.  - Then, JNJ announced a dividend, and my broker cancelled the trailing stop order.  I've re-entered a ""Stop market"" order at 113.45.  I've also entered an alert for $126.07 -- if the alert gets triggered, I'll cancel the Market Stop and enter a new trailing stop." It's done by Opening Auction (http://www.advfn.com/Help/the-opening-auction-68.html): The Opening Auction Between 07.50 and   a random time between 08.00 and   08.00.30, there will be called an auction period during which time,   limit and market orders are entered   and deleted on the order book. No   order execution takes place during   this period so it is possible that the   order book will become crossed. This   means that some buy and sell orders   may be at the same price and some buy   orders may be at higher prices than   some sell orders. At the end of the random start period,   the order book is frozen temporarily   and an order matching algorithm is   run. This calculates the price at   which the maximum volume of shares in   each security can be traded. All   orders that can be executed at this   price will be filled automatically,   subject to price and priorities. No   additional orders can be added or   deleted until the auction matching   process has been completed. The opening price for each stock will   be either a 'UT' price or, in the   event that there are no transactions   resulting form the auction, then the   first 'AT' trade will be used. "if it opens below my limit order  What exactly are you trying to achieve here? If your limit order is for 100 and the stock opens ""below"" your limit order, say 99, then it is obviously going to buy it automatically.  also place a stop loss on the same order  Most brokers allow limit + stop loss order at the same time on same order.  What I conclude from your question is that you're with a broker that is using obscure technology. Get a better broker or maybe, retry phrasing your question correctly." Depending on your strategy, it could be though there is also something to be said for what kind of order are you placing: Market, limit or otherwise? Something else to consider is whether or not there is some major news that could cause the stock/ETF to gap at the open.  For example, if a company announces strong earnings then it is possible for the stock to open higher than it did the previous day and so a market order may not to take into account that the stock may jump a bit compared to the previous close.  Limit orders can be useful to put a cap on how much you'll pay for a stock though the key would be to factor this into your strategy of when do you buy. This is often the case where traders are closing out short positions they don't want to hold overnight, for a variety of reasons that matter to them.  Most frequently, this is from day traders or high-frequency traders settling their accounts before the markets close. "The risk of market orders depends heavily on the size of the market and the exchange. On big exchange and a security which is traded in hue numbers you're likely that there are enough participants to give you a ""fair"" price. Doing a market order on a security which is hardly dealed you might make a bad deal. In Germany Tradegate Exchange and the sister company the bank Tradegate AG are known to play a bit dirty: Their market is open longer than Frankfurt (Xetra) and has way lower liquidity. So it can happen that not all sell or buy orders can be processes on the Exchange and open orders are kept. Then Tradegate AG steps in with a new offer to full-fill these trades selling high or buying low. There is a German article going in details on wiwo.de either German or via Google Translate" 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? At any point of time, buyer wants to purchase a stock at lesser price and seller wants to sell the stock at a higher price.  Let's consider this scenario  Company XYZ is trading at 100$, as stated above buyer wants to purchase at lower price and seller at higher price, this information will be available in Market depth, let's consider there are 5 buyers and 5 sellers, below are the details of their orders Buyers List Sellers List Highest order in buyers list will contain the bid price and bid quantity, Lowest order in Sellers list will contain the offer price and offer quantity. Now, if I want to buy 50 Stocks of company XYZ, need to place an order first, it can be either limit or Market. Limit Order : In this order, I will mention the price(buy price) at which I wish to buy, if there is any seller selling the stock less than or equal to price I have mentioned, then the order will be executed else it will be added to buyers list Market Order : In this order, I will not mention the price, if I wish to purchase 50 Stocks, then it will find the lowest offer price and buy stocks, in our case it will be 101. if I wish to purchase 200 Stocks, then it will find the lowest offer price and buy stocks, in our case it will be 2 transactions, since entire request cannot be accommodated in single order Usually the volume(Ask Volume and Offer Volume) being displayed are all Limit orders and not Market orders, Market orders are executed immediately. This is just an example, However several transactions are executed within a second, hence we will get to know the exact value only after the order is completed(executed) "- 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" In the stock market many participants enter orders that are not necessarily set at the current market price of the stock (i.e. they are not market orders, they are limit orders). They can be lower than the market price (if they want to buy) or they can be higher than the market price (if they want to sell). The set of orders at each point of time for a security is called the order book. The lowest selling price of the order book is the offer or ask, the higher buying price is the bid. The more liquid is a security, the more orders will be in the order book, and the narrower will be the bid-ask spread. The depth of the order book is the number of units that the order book can absorb in any direction (buy or sell). As an example: imagine I want to buy 100 units at the lowest offer, but the size of the lowest offer is only 50 units, and there is not any further order, that means the stock has little depth. "You can place the orders like you suggested.  This would be useful in a market that is moving quickly where you want to be reasonably sure of execution but don't want the full exposure of a market order.  This won't jump your spot in the queue though in the sense that you won't get ahead of other orders that are ""ready"" for execution just because you have crossed the spread aggressively." "The SEC reference document (PDF) explains order types in more detail. A fill-or-kill order is neither a market order nor a limit order; instead it's something in between. A market order asks to be filled at the best available price, whatever that price might be when the order gets to the exchange.  Additionally, if there are not enough counterparties to fill the order at the best available price, then part of the order may be filled at a worse price.  This all happens more or less immediately; there's no way to cancel it once it has been placed. A limit order asks to be filled at a particular price, and if no counterparties want to trade at that price right now, then the order will just sit around all day waiting for someone to agree on the price; it can be canceled at any time. A fill-or-kill order asks to be filled at a particular price (like a limit order), but if that price or a better one is not currently available then the order is immediately canceled.  It does not accept a worse price (the way a market order does), nor does it sit around waiting (the way a limit order does).  Since the exchange computes whether to ""fill"" or ""kill"" the order as soon as it is arrives, there's also no way to cancel it (like a market order)." Do not use a stop loss order as a long-term investor.  The arguments in favor of stop losses being presented by a few users here rely on a faulty premise, namely, that there is some kind of formula that will let you set your stop such that it won't trigger on day-to-day fluctuations but will trigger in time to protect you from a significant loss in a serious market downturn.  No such formula exists.  No matter where you set your stop, it is as likely to dump you from your investment just before it begins climbing again as it is to shield you from continued losses.  Each time that happens, you will have sold low and bought high, incurring trading fees into the bargain.  It is very unlikely that the losses you avoid in a bear market (remember, you still incur the loss up until your stop is hit; it's only the losses after that that you avoid) will make up the costs of false alarms. On top of that, once you have stopped out of your first investment choice, then what?  Will you reinvest in some other stock or fund?  If those investments didn't look good to you when you first set up your asset allocation, then why should they look any better now, just because your primary investment has dropped by some arbitrary[*] amount?  Will you park the money in cash while you wait for prices to bottom out?  The market bottom is only apparent in retrospect.  There is no formula for calling it in real time. Perhaps stop loss orders have their uses in active trading strategies, or maybe they're just chrome that trading platforms use to attract customers.  Either way, using them on long-term investments will just cost you money in the long run.  Forget the fancy order types, and manage your risk through your asset allocation.  The overwhelming likelihood is that you will get better performance, and you will spend less time worrying about your investments to boot. [*] Why are the stop levels recommended by the formulae invariably multiples of 5%?  Do the market gods have a thing for round numbers?