Why would we need a “stop-limit order” for selling?
If one wants to have a bound on the loss percentages that are acceptable, this is would be a way to enforce that. For example, suppose someone wants to have a 5% stop-loss but doesn't want this to be worse than 10% as if the stock goes down more than 10% then the sell shouldn't happen. Thus, if the stock opened in a gap down 15% one day, this triggers the stop-loss and would exit at too low of a price as the gap was quite high as I wonder how familiar are you with how much a stock's price could change that makes the prices not be as continuous as one would think. At least this would be my thinking on a volatile stock where one may want to try to limit losses if the stock does fall within a specific range. "One practical application would be to protect yourself from a ""flash crash"" type scenario where a stock suddenly plunges down to a penny due to transient market glitches. If you had a stop-loss order that executed at a penny (for a non-penny stock) it would be probably be voided by the exchange, but you might not want to take that risk." "An important thing that many people fail to realize is that the number of shares outstanding in a stock, times the current market price of those shares, does not represent anything related to the total value of those shares.  If a company has one million shares outstanding and its total value is $10 million, then the real worth of each share is $10.  If few people feels like buying or selling, but a few people think the company is worth $50 million and offer $50/share, that could raise the market price to $50/share, but it wouldn't mean that the company became worth five times as much; it would merely mean the stock was overpriced. If, after the price went to $50/share, all the owners of the stock put in stop-loss orders at $45.  Note that the real $10/share ""real value"" of their stock would never have changed.  If the people who thought the stock was worth $50 decided to get out of the market, and nobody else was willing to offer more than $10, that would instantly drop the price to $10.  The fact that a million shares of stock have stop-loss orders at $45 wouldn't magically generate buyers for those stocks at that price.  Indeed, unchecked stop-loss orders would have the reverse effect, since many people who would have been willing if not eager to buy the stock if it had been available for less than $10/share would instead be trying to sell it below that price. It's too bad people think that the number of shares outstanding times the current market price represents some kind of ""meaningful quantity"".  If the present cash value of all future payouts associated with a share of stock is $10, then someone who buys a share of stock for less than that makes money off the seller; someone who pays more loses money to the seller.  Many people think they can lose money to the seller and still come out okay if the price goes higher, but what that really means is that they're hoping to find a bigger sucker--a game where it's guaranteed that some people will have losses they don't recoup."
This is to protect your position in specific highly volatile market conditions.  If the stock is free falling and you only have a stop order at $90, it's possible that this order could be filled at $50 or even less. The limit is to protect you from that, as there are certain very specific times where it's better to just hold the stock instead of taking a huge loss (ie when price is whipsawing). 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). If you want your order to go through no matter what then you should be using market orders rather than limit orders. With limit orders you may get the price you are after or better but you are not guaranteed to get your order transacted. With a market order you are guaranteed to get you order transacted but may get a price inferior to what you were after. Most times this should only be a few cents but can get much larger in a fast moving or less liquid market. You should incorporate this slippage into your trading plan. Maybe a better option for you, if you are looking at + or - 0.5% from the last price, would be to use conditional triggers (stop buy and sell orders) with your market orders. Once the market moves in your direction your conditional order will be triggered and the stock will be bought at current market price. No, Mark is right, if you place a market order there will always be someone to buy or sell at the market price.  Only if you place a limit order on the price can it not sell or be bought.  Just research on your computer and you will find your answer.  You must be specify about open order or limit order when asking. I assume you're talking about a sell order, not a buy order. When you place a limit sell order, your order is guaranteed to be placed at that price or higher.  If the market is currently trading much higher than the price of your sell order, then your mistakenly low limit order will be essentially a market order, and will be filled at  the current bid price. So the only way this is a problem is if you want to place a limit sell that is much higher than the current market, but mistakenly place a limit lower than the current market. If you want to make sure you pay at or below a specific price per share, use a limit order. If you want to buy the stock close to the current price, but aren't price sensitive, use a market order. Market orders are typically not a great idea because if you're buying thousands or tens of thousands of shares this can mean a large swing in cost if the market suddenly changes direction. From your question, I am guessing that you are intending to have stoploss buy order. is the stoploss order is also a buy order ?  As you also said, you seems to limit your losses, I am again guessing that you have short position of the stock, to which you are intending to place a buy limit order and buy stoploss order (stoploss helps when when the price tanks). And also I sense that you intend to place buy limit order at the price below the market price. is that the situation?  If you place two independent orders (one limit buy and one stoploss buy). Please remember that there will be situation where two orders also get executed due to market movements. Add more details to the questions. it helps to understand the situation and others can provide a strategic solution. "Correcting Keith's answer (you should have read about these details in the terms and conditions of your bank/broker): Entrustment orders are like a ""soft"" limit order and meaningless without a validity (which is typically between 1 and 5 days). If you buy silver at an entrustment price above market price, say x when the market offer is m, then parts of your order will likely be filled at the market price.  For the remaining quantity there is now a limit, the bank/broker might fill your order over the next 5 days (or however long the validity is) at various prices, such that the overall average price does not exceed x. This is different to a limit order, as it allows the bank/broker to (partially) buy silver at higher prices than x as long as the overall averages is x or less.  In a limit set-up you might be (partially) filled at market prices first, but if the market moves above x the bank/broker will not fill any remaining quantities of your order, so you might end up (after a day or 5 days) with a partially filled order. Also note that an entrustment price below the market price and with a short enough validity behaves like a limit price. The 4th order type is sort of an opposite-side limit price: A stop-buy means buy when the market offer quote goes above a certain price, a stop-sell means sell when the market bid quote goes below a certain price. Paired with the entrusment principle, this might mean that you buy/sell on average above/below the price you give. I don't know how big your orders are or will be but always keep in mind that not all of your order might be filled immediately, a so-called partial fill.  This is particularly noteworthy when you're in a pro-rata market." You talk about an individual not being advised to sell (or purchase) in response to trends in the market in such a buy and hold strategy. But think of this for a moment: You buy stock ABC for $10 when both the market as a whole and stock ABC are near the bottom of a bear market as say part of a value buying strategy. You've now held stock ABC for a number of years and it is performing well hitting $50. There is all good news about stock ABC, profit increases year after year in double digits. Would you consider selling this stock just because it has increased 400%. It could start falling in a general market crash or it could keep going up to $100 or more. Maybe a better strategy to sell ABC would be to place a trailing stop of say 20% on the highest price reached by the stock. So if ABC falls, say in a general market correction, by less than 20% off its high and then rebounds and goes higher - you keep it. If ABC however falls by more than 20% off its high you automatically sell it with your stop loss order. You may give 20% back to the market if the market or the stock crashes, but if the stock continues going up you benefit from more upside in the price. Take AAPL as an example, if you bought AAPL in March 2009, after the GFC, for about $100, would you have sold it in December 2011 when it hit $400. If you did you would have left money on the table. If instead you placed a trailing stop loss on AAPL of 20% you would have been still in it when it hit its high of $702 in September 2012. You would have finally been stopped out in November 2012 for around the $560 mark, and made an extra $160 per share. And if your thinking, how about if I decided to sell AAPL at $700, well I don't think many would have picked $700 as the high in hindsight. The main benefit of using stop losses is that it takes your emotions out of your trading, especially your exits. "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." "During market hours, there are a lot of dealers offering to buy and sell all exchange traded stocks. Dealers don't actually care about the company's fundamentals and they set their prices purely based on order flow. If more people start to buy than sell, the dealer notices his inventory going down and starts upping the price (both his bid and ask). There are also traders who may not be ""dealers"", but are willing to sell if the price goes high enough or buy if the price goes low enough. This keeps the prices humming along smoothly. During normal trading hours, if you buy something and turn around and sell it two minutes later, you'll probably be losing a couple cents per share. Outside normal market hours, the dealers who continue to have a bid and ask listed know that they don't have access to good price information --  there isn't a liquid market of continuous buying and selling for the dealer to set prices he considers safe. So what does he do? He widens the spread. He doesn't know what the market will open tomorrow at and doesn't know if he'll be able to react quickly to news. So instead of bidding $34.48 and offering at $34.52, he'll move that out to $33 and $36. The dealer still makes money sometimes off this because maybe some trader realized that he has options expiring tomorrow, or a short position that he's going to get a margin call on, or some kind of event that pretty much forces him to trade. Or maybe he's just panicking and overreacting to some news. So why not trade after hours? Because there's no liquidity, and trading when there's no liquidity costs you a lot." "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." "That's the way the markets work in THEORY. In actual fact, markets are subject to ""real world"" pressures. That is, there are so many things going on in the market that the end of the ""Lined In"" lock up is just one of many. To produce the result you describe, traders would have to hold cash in reserve for this so-called ""contingency"" to buy at the end of the lock-up. In most cases, they wouldn't want to because of everything else that is going on.  To use a real world analogy, would you want to wait until the last possible moment before going to the bathroom? Or would you go now while you had the chance? That's what the decision about ""holding cash in reserve for a contingency"" is like." The Bank Secrecy Act of 1970 requires that banks assist the U.S. Gov't in identifying and preventing money laundering. This means they're required to keep records of cash transactions of Negotiable Instruments, and report any such transactions with a daily aggregate limit of a value greater than (or equal to?) $10,000. Because of this, the business which is issuing the money order is also required to record this transaction to report it to the bank, who then holds the records in case FinCEN wants to review the transactions. EDITED: Added clarification on the $10,000 rule From a mathematical expected-value standpoint, there is no difference between gambling (e.g. buying a lottery ticket) and investing (e.g. buying a share of stock).  The former probably has negative expected value while the latter probably has positive expected value, but that is not a distinction to include in a definition (else every company that gives a bad quarterly earnings report suddenly changes categories). However, investment professionals have a vested interest in claiming there is a difference; that justifies them charging fees to steer you into the right investment.  Consequently, hair-splitting ideas like the motive behind a purchase are introduced.  The classification of an item to be purchased should not depend on the mental state of its purchaser. Depending on the situation, it may be right to engage in negative EV behavior.  For example, if you have $1000 and need $2000 by next week or else you can't have an operation and you will die (and you can't find anyone to give you a loan).  Your optimal strategy is to gamble your $1000, at the best odds you can get, with a possible outcome of $2000.  So even if you only have a 1/3 chance of winning and getting that operation, it's still the right bet if you can't find a better one.