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."
You are correct, a possible Dead Cat Bounce is forming on the stock markets. If it does form it will mean that prices have not reached their bottom, as this pattern is a bearish continuation pattern. For a Dead Cat Bounce to form prices will need to break through support formed by the lows last week. If prices bounce off the support and go back up it could become a double bottom pattern, which is a reversal pattern. The double bottom would be confirmed if prices break above the recent high a couple of days ago. Regarding the psychology of the dead cat bounce pattern, is that after a distinct and quick reversal of prices from recent highs you have 2 groups of market participants who create demand in the market. Firstly you have those who were short covering their short positions to take profits, and secondly you have those who are looking for a bargain buying at what they think is the low. So for a few days you have the bulls taking over the bears.  Then as more less positive news comes in, the bears hit the market again. These are more participants opening short positions, but more so those who missed out in selling previously because prices fell too quickly, seeing another opportunity to sell at a better price. So the bears take over again.  Unless there is very good news around the corner it is likely that the bears will stay in control and prices will fall further. How to trade a dead cat bounce (assuming you have been stopped out of your long possistions already)? If you are aggressive you can go short as prices start reversing from the top of the bounce (with your stop loss just above the top of the bounce). If you are more conservative you would place your entry for a short position just below the support at the start of the bounce (with your stop above the top of the bounce). You could also place an order for a long position above the top of the bounce if a double bottom eventuated. A One Cancels the Other (OCO) would be an appropriate order for such a situation. "If there is a very sudden and large collapse in the exchange rate then because algorithmic trades will operate very fast it is possible to determine “x” immediately after the change in exchange rate. All you need to know is the order book. You also need to assume that the algorithmic bot operates faster than all other market participants so that the order book doesn’t change except for those trades executed by the bot. The temporarily cheaper price in the weakened currency market will rise and the temporarily dearer price in the strengthened currency market will fall until the prices are related by the new exchange rate. This price is determined by the condition that the total volume of buys in the cheaper market is equal to the total volume of sells in the dearer market.   Suppose initially gold is worth $1200 on NYSE or £720 on LSE. Then suppose the exchange rate falls from r=0.6 £/$ to s=0.4 £/$.  To illustrate the answer lets assume that before the currency collapse the order book for gold on the LSE and NYSE looks like: GOLD-NYSE   Sell (100 @ $1310) Sell (100 @ $1300) <——— Sell (100 @ $1280) Sell (200 @ $1260) Sell (300 @ $1220) Sell (100 @ $1200) ————————— buy (100 @ $1190) buy (100 @ $1180)   GOLD-LSE Sell (100 @ £750) Sell (100 @ £740) ————————— buy (200 @ £720) buy (200 @ £700) buy (100 @ £600) buy (100 @ £550) buy (100 @ £530) buy (100 @ £520) <——— buy (100 @ £500)   From this hypothetical example, the automatic traders will buy up the NYSE gold and sell the LSE gold in equal volume until the price ratio ""s"" is attained. By summing up the sell volumes on the NYSE and the buy volumes on the LSE, we see that the conditions are met when the price is $1300 and £520. Note 800 units were bought and sold.   So “x” depends on the available orders in the order book. Immediately after this, however, the price of the asset will be subject to the new changes of preference by the market participants. However, the price calculated above must be the initial price, since otherwise an arbitrage opportunity would exist." Typically this isn't a random order- having a small volume just means it's not showing on the chart, but it is a vlid price point. Same thing would've happened if it would've been a very large order that shows on the chart. Consider also that this could have been the first one of many transactions that go far below your stop point - would you not have wanted it to be executed then, at this time, as it did? Would you expect the system to look into future and decide that this is a one time dip, and not sell; versus it is a crash, and sell? Either way, the system cannot look in the future, so it has no way to know if a crash is coming, or if it was a short dip; therefore the instrcutions are executed as given - sell if any transfer happens below the limit. To avoid that (or at least reduce the chance for it), you can either leave more distance (and risk a higher loss when it crashes), or trade higher volumes, so the short small dip won't execute your order; also, very liquid stocks will not show such small transaction dips. At any point of time, buyer wants to purchase a stock at lesser price and seller wants to sell the stock at a higher price.  Let's consider this scenario  Company XYZ is trading at 100$, 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) I have done this, and the reason is to make sure that I don't run out of money in my account to place the order if there is an unexpected upswing in price. Suppose I have $1000 in my account and I want to buy 10 shares of ABCD that are currently at $99.  If the price doesn't change, then I am all set, but if the price goes up to $101 then I don't have sufficient funds to make the purchase. By placing a limit order at $100 I can ensure that I have enough money to place the order. In general, it is a rather unlikely scenario that it could happen, but placing the limit order is easy to do and it gives me peace of mind. I don't know what you mean about bypassing the queue. Market orders can be reasonably safe when dealing with stocks that are rather liquid and have quite low volatility. But it's important to note that you're trading a large degree of control over your buy / sell price for a small benefit in speed or complexity of entering an order. I always use limit orders as they help me guard against unexpected moves of the stock. Patience and attention to details are good qualities to have as an investor. There isn't a formula like that, there is only the greed of other market participants, and you can try to predict how greedy those participants will be. If someone decided to place a sell order of 100,000 shares at $5, then you can buy an additional 100,000 shares at $5. In reality, people can infer that they might be the only ones trying to sell 100,000 shares right then, and raise the price so that they make more money. They will raise their sell order to $5.01, $5.02 or as high as they want, until people stop trying to buy their shares. It is just a non-stop auction, just like on ebay. Consider the mechanic which actually drives the 'price' of a stock. In simplest terms, the 'price' of a stock is the price at which the most recent trade occurred. ie: if the price of IBM is $100/share, that means the last time someone bought IBM stock, they paid $100. Above and below the 'spot price', are dozens/hundreds/thousands of buyers and sellers who have placed orders that no one is yet willing to match. ie: if IBM's spot price is at $100, there could still be 10,000 people willing to sell for $101 (called the 'ask' price, for the lowest price someone is currently willing to sell at), and 15,000 willing to buy for $99 (called the 'bid' price, for the highest price someone is currently willing to buy for).  Until someone is willing to buy for $101, then no one will be able to sell at $101. Until someone is willing to sell for $99, no one will be able to buy for $99. Typically orders are placed in the market at a particular limit. Meaning that those orders to buy at $99/sell at $101 are already in the 'system', and will be matched immediately as soon as someone is willing to meet the price on the other side. Now consider general market economics: high demand drives up price, and high supply drives down price. If the details above for IBM were yesterday, and today some news came out that IBM was laying off employees, imagine that another 10,000 people who held shares wanted to sell. Now there would be 20,000 sellers and only 15,000 buyers. If those new sellers were aggressive about wanting to sell, they would have to drop their price to $99, to match the highest buyers in the market. Put together, this means that as more sellers enter the market, supply of shares increases, driving down price. Conversely, as more buyers enter the market, demand for shares increases, driving up share price. As a result of the above, you can say that (all else being equal) if price for a stock goes up, there were more buyers that day, and if price goes down, there were more sellers that day. On the face of it, that is not necessarily true, because you could have the same number of buyers and sellers, one side could have simply decreased/increased their acceptable price to match the other side.