Can a buy market order be matched with a sell market order in Forex trading?
"If there are no limit orders on the opposite side of the book when your market order gets its turn for execution, it should be rejected by the market.  A market order should generally not ""sit on the book"" like your question suggests waiting for another order to arrive.  Thus, the situation that you describe should not happen in an ordinary market that is operating in an orderly fashion. This is not to say that your order cannot ""sit"" for a while in a queue - If there is heavy volume, orders will be executed in order, so your your market order may have to wait for orders entered ahead of it to be processed.  But once its turn comes up, that's it. There are some related points to consider: I should caution that my answer is biased a bit to US stock markets, whereas you asked about currency markets.  I believe the same basic principles apply, but I'd be swayed by someone with evidence to the contrary.  I'd also note that currency tends to be more liquid than stock, so I think it's less likely that this situation would come up.  Maybe possible for a ""weak"" currency or a currency that experiences a sudden crisis of some sort." Based on my research while asking How are unmarketable market orders (other side of the order book is empty) matched with incoming orders? and the one answer there, it seems like there are a few things for certain: All of this of course depends on the exact algorithm specified by the given exchange - I don't think there's a standard here.
It is unlikely that buying 100 shares will have any effect on a stock's price, unless the stock's average trading volume is incredibly low.  That being said, no matter how many share you buy, there's no way to know what the impact on the price will be, because that's only one factor in how shares are priced.  If anyone could figure out the answer to your question then they'd be extremely rich, because they'd simply watch for big share trades and then buy those stocks on the way up. The market makers who actually execute the trades are the ones who set the prices, and most stocks have multiple market makers trading the stock, so the bid/ask you see is the highest bid and lowest ask.  The market makers set the price based on what the trend of the stock is.  If, for instance, there's a large number of sell orders against a stock, the market makers will start dropping the bid prices as they fill execution orders, and as they see buy orders increase, they'll raise ask prices as they fill execution orders.  The market makers earn the difference between what they paid to buy someone's stock who was selling and what they get from someone else who buys it. This is a simplified explanation, so pro traders, don't beat me up! (grin) So, basically, it takes quite a bit of share volume in one direction or another to affect a stock's price.  I can guarantee a 100-share trade wouldn't even be noticed by market makers. I hope this helps. Good luck! "There are two distinct questions that may be of interest to you. Both questions are relevant for funds that need to buy or sell large orders that you are talking about. The answer depends on your order type and the current market state such as the level 2 order book. Suppose there are no iceberg or hidden orders and the order book (image courtesy of this question) currently is:  An unlimited (""at market"") buy order for 12,000 shares gets filled immediately: it gets 1,100 shares at 180.03 (1,100@180.03), 9,700 at 180.04 and 1,200 at 180.05. After this order, the lowest ask price becomes 180.05 and the highest bid is obviously still 180.02 (because the previous order was a 'market order'). A limited buy order for 12,000 shares with a price limit of 180.04 gets the first two fills just like the market order: 1,100 shares at 180.03 and 9,700 at 180.04. However, the remainder of the order will establish a new bid price level for 1,200 shares at 180.04. It is possible to enter an unlimited buy order that exhausts the book. However, such a trade would often be considered a mis-trade and either (i) be cancelled by the broker, (ii) be cancelled or undone by the exchange, or (iii) hit the maximum price move a stock is allowed per day (""limit up""). Funds and banks often have to buy or sell large quantities, just like you have described. However they usually do not punch through order book levels as I described before. Instead they would spread out the order over time and buy a smaller quantity several times throughout the day. Simple algorithms attempt to get a price close to the time-weighted average price (TWAP) or volume-weighted average price (VWAP) and would buy a smaller amount every N minutes. Despite splitting the order into smaller pieces the price usually moves against the trader for many reasons. There are many models to estimate the market impact of an order before executing it and many brokers have their own model, for example Deutsche Bank. There is considerable research on ""market impact"" if you are interested. I understand the general principal that when significant buy orders   comes in relative to the sell orders price goes up and when a   significant sell order comes in relative to buy orders it goes down. I consider this statement wrong or at least misleading. First, stocks can jump in price without or with very little volume. Consider a company that releases a negative earnings surprise over night. On the next day the stock may open 20% lower without any orders having matched for any price in between. The price moved because the perception of the stocks value changed, not because of buy or sell pressure. Second, buy and sell pressure have an effect on the price because of the underlying reason, and not necessarily/only because of the mechanics of the market. Assume you were prepared to sell HyperNanoTech stock, but suddenly there's a lot of buzz and your colleagues are talking about buying it. Would you still sell it for the same price? I wouldn't. I would try to find out how much they are prepared to buy it for. In other words, buy pressure can be the consequence of successful marketing of the stock and the marketing buzz is what changes the price." "It depends on many factors, but generally, the bid/ask spread will give you an idea. There are typically two ways to buy (or sell) a security: With a limit order, you would place a buy for 100 shares at $30-. Then it's easy, in the worst case you will get your 100 shares at $30 each exactly. You may get lucky and have the price fall, then you will pay less than $30. Of course if the price immediately goes up to say $35, nobody will sell at the $30 you want, so your broker will happily sit on his hands and rake in the commission while waiting on what is now a hail Mary ask. With a market order, you have the problem you mention: The ticker says $30, but say after you buy the first 5 shares at $30 the price shoots up and the rest are $32 each - you have now paid on average $31.9 per share. This could happen because there is a limit order for 5 at $30 and 200 at $32 (you would have filled only part of that 200). You would be able to see these in the order book (sometimes shown as bid/ask spread or market depth). However, the order book is not law. Just because there's an ask for 10k shares at $35 each for your $30 X stock, doesn't mean that by the time the price comes up to $35, the offer will still be up. The guy (or algorithm) who put it up may see the price going up and decide he now wants $40 each for his 10k shares. Also, people aren't obligated to put in their order: Maybe there's a trader who intends to trade a large volume when the price hits a certain level, like a limit order, but he elected to not put in a limit order and instead watch the ticker and react in real time. Then you will see a huge order suddenly come in out of nowhere. So while the order book is informative, what you are asking is actually fundamentally impossible to know fully, unless you can read the minds of every interested trader. As others said, in ""normal"" securities (meaning traded at a major exchange, especially those in the S&P500) you simply can't move the price, the market is too deep. You would need millions of dollars to budge the price, and if you had that much money, you wouldn't be asking here on a QA site, you would have a professional financial advisor (or even a team) that specializes in distributing your large transaction over a longer time to minimize the effect on the market. With crazier stocks, such as OTC and especially worthless penny stocks with market caps of $1 mil or less, what you say is a real problem (you can end up paying multiples of the last ticker if not careful) and you do have to be careful about it. Which is why you shouldn't trade penny stocks unless you know what you're doing (and if you're asking this question here, you don't)." You'd need millions of dollars to trade the number of shares it would take to profit from these penny variations.  What you bring up here is the way high frequency firms front-run trades and profit on these pennies. Say you have a trade commission of $5.  Every time you buy you pay $5, every time you sell you pay $5.  So you need a gain in excess of $10, a 10% gain on $100.  Now if you wanted to trade on a penny movement from $100 to $100.01, you need to have bought 1,000 shares totaling $100,000 for the $0.01 price movement to cover your commission costs.  If you had $1,000,000 to put at risk, that $0.01 price movement would net you $90 after commission, $10,000,000 would have made you $990.  You need much larger gains at the retail level because commissions will equate to a significant percentage of the money you're investing. Very large trading entities have much different arrangements and costs with the exchanges.  They might not pay a fee on each transaction but something that more closely resembles a subscription fee, and costs something that more closely resembles a house. Now to your point, catching these price movements and profiting.  The way high frequency trading firms purportedly make money relates to having a very low latency network connection to a particular exchange.  Their very low latency/very fast network connection lets them see orders and transact orders before other parties.   Say some stock has an ask at $101 x 1,000 shares.  The next depth is $101.10.  You see a market buy order come in for 1,000 shares and place a buy order for 1,000 shares at $101 which hits the exchange first, then immediately place a sell order at $101.09, changing the ask from $101.00 to $101.09 and selling in to the market order for a gain of $0.09 per share. "When there is a trade the shares were both bought and sold. In any trade on the secondary market there has to be both a buyer and a seller for the trade to take place. So in ""lasttradesize"" a buyer has bought the shares from a seller." Gold is traded on the London stock exchange (LSE) and the New York stock exchange (NYSE) under various separate asset tickers, mainly denominated in sterling and US dollars respectively.  These stocks will reflect FX changes very quickly.  If you sold LSE gold and foreign exchanged your sterling to dollars to buy NYSE gold you would almost certainly lose on the spreads upon selling, FX'ing and re-buying. In short, the same asset doesn't exist in multiple currencies.  It may have the same International Securities Identification Number (ISIN), but it can trade with different Stock Exchange Daily Official List (SEDOL) identifiers, reflecting different currencies and/or exchanges, each carrying a different price at any one time. Foreign Exchange (Forex) trading is extremely difficult to do profitably over time – for retail investors and institutional investors alike. Many Forex traders enter the markets with hope of a profitable trading adventure, only to find themselves overwhelmed by the complexity of the markets. Binary options trading enables traders who have experienced difficulty in the Forex market to trade options. 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).