When are stop market/limit orders visible on the open market?
From the non-authoritative Investopedia page: A stop-limit order will be executed at a specified price, or better, after a given stop price has been reached. Once the stop price is reached, the stop-limit order becomes a limit order to buy or sell at the limit price or better. So once the stop price has been breached, your limit order is placed and will be on the order books as a $9 ask. For a vanilla stop order, a market order will be placed and will be filled using the highest active bid(s).
It will depend largely on your broker what type of stop and trailing stop orders they provide. Saying that, I have not come across any brokers yet that offer limit orders with trailing stop orders.  Unlike a standard stop order where you can either make it a market stop order or a limit stop order, usually most brokers have trailing stop orders as market orders only, where you can either set the trailing stop to be a dollar value or percentage from the most recent high. Remember also, that trailing stop orders will be based on the intra-day highs and not the highest closing price. That means that if the share price spikes up during the day your trailing stop will move up, and if the price then spikes down you may be stopped out prematurely, after which the price might rally again. For this reason I try to base my trailing stops on the highest closing price by using standard stop loss orders and moving it up manually after the close of trade if the share price has closed at a new high. This takes a few minutes each evening (depending on how many stocks you have to check and adjust the stops for) but gives you more control. Using this method will also enable you to set limit orders attached to your stop loss triggers, and you won't have to keep your trailing too close to the last high price thus potentially causing you to get stopped out prematurely. Slightly off track but may be handy if you set profit targets, my broker has recently introduced Trailing Take Profit Orders. The way it works is, say you have a profit target of 50%, so you buy at $2 and want to take profits if the price reaches $3, you could set your Trailing Take Profit Trigger at say $3.10 or above and set a Trail by Amount of say $0.10. So if the price after hitting $3.10 falls to $3.00 you will be stopped out and collect your profits. If the price moves up to $3.30 and then falls to $3.20, you will be stopped out at $3.20 and make some extra profits. If the price continues going up the Trailing Take Profit will continue to move up always $0.10 below the highest price reached. I think this would be a very useful order if you were range trading where you could set the Trailing Take Profit trigger near recent resistance so you can get out if prices start reversing at or around the resistance, but continue profiting if the price breaks through the resistance. "After learning about things that happened in the ""flash crash"" I always use limit orders. In an extremely rare instance if you place a market order when there is a some glitch, for example some large trader adds a zero at the end of their volume, you could get an awful price.  If I want to buy at the market price, I just set the limit about 1% above the market price. If I want to sell, I set the limit 1% below the market price. I should point out that your trade is not executed at the limit price. If your limit price on a buy order is higher than the lowest offer, you still get filled at the lowest offer. If before your order is submitted someone fills all offers up to your limit price, you will get your limit price. If someone, perhaps by accident, fills all orders up to twice your limit price, you won't end up making the purchase. I have executed many purchases this way and never been filled at my limit price." When using the Stochastic Indicator your basic aim is to buy (go long) when the stochastic becomes oversold (goes below 20%) and then the %K line crosses above the %D line at a market low, and to sell (go short) when the stochastic becomes overbought (goes above 80%) and then the %K line crosses below the %D line at a market high. Other indicators or candlestick patters can also be used to further confirm the trade. Below is a chart of a trade I recently took on GUD.AX using the Slow Stochastic in combination with support and resistance levels as well as a candlestick pattern.  When I conducted my stock search on the evening of 28th July 2015, GUD was one of the results from the search that I particularly liked. The Slow Stochastic had just made a crossover in the oversold area just as the price was bouncing off its recent lows at the support line. But what I really like about this opportunity was that there was also a bullish reversal candle (a Hammer) at this short term market bottom. The high for the day was $8.34, so I placed a stop buy order to buy the stock tomorrow if the price opened or moved above this high of today. So I would only buy if the stock hit or moved above $8.35 during the next days trading. So if the stock opened and stayed below the previous day's high I would not buy the stock and my order would be canceled at the end of the day. This is very important because it stops you from getting into trades that don't go in the direction you want. If this happens then you could check the chart again after market close to see if it is still worthwhile to place a new order for the next day. On the 29th July 2015 the stock did open higher at $8.42 (which is where my order got executed) and closed at $8.46. So I ended up buying slightly above my target price but it did move higher on the day, so a successful entry overall. I had placed my initial stop loss at $8.09 (just below the low of the previous day of $8.10). If the trade had gone against me in the following days the most I would have lost was 1% of my total account capital. My target for this trade was $9.86 (just below the resistance line near $10), which would represent a 5% gain against my total account capital (or approx. 16.7% gain on the trade). So my win to loss ratio was 5:1. As you can see from the chart, the next day gapped up at the open and prices continued moving up strongly during the day. The next day was a slightly negative day, and then a few days later, on the 5th August 2015 my target price of $9.86 was reached (with a high of $9.88 for that day), so my order was closed for a total profit of 16.7% on the face value of the trade. However, as I bought on margin (using CFDs) my actual profit on the initial margin I had invested was 167%. My total time in the trade was 7 days, and I spent about an hour in the evening doing my searches and placing my orders, then less than 10 minutes managing the trade each evening after market close. The stock did go up a bit further after my profit target was reached, but the day after that the price started to fall as the price hit the resistance line and the Slow Stochastic did a crossover in the overbought area. Overall, this was a very ideal trade and I was very happy with it. Not all my trades reach my profit targets and I may get stopped out at a smaller profit or I might make a small loss (as I move my stops up as the price moves up). The key to successful trading over the long term is to keep you losses small and let your profits run (with my longer term trend trading I don't have profit targets and let my profits run until I get stopped out, but with my shorter term trading I do use a profit target usually 5 or 6 times the size of my initial stop). If you have an average win to average loss ratio of 3:1 or higher and have a success rate of 50% winners you will make money over the long term. 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. 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. In my experience thanks to algorithmic trading the variation of the spread and the range of trading straight after a major data release will be as random as possible, since we live in an age that if some pattern existed at these times HFT firms would take out any opportunity within nanoseconds. Remember that some firms write algorithms to predict other algorithms, and it is at times like those that this strategy would be most effective. With regards to my own trading experience I have seen orders fill almost €400 per contract outside of the quoted range, but this is only in the most volatile market conditions. Generally speaking, event investing around numbers like these are only for top wall street firms that can use co-location servers and get a ping time to the exchange of less than 5ms. Also, after a data release the market can surge/plummet in either direction, only to recover almost instantly and take out any stops that were in its path. So generally, I would say that slippage is extremely unpredictable in these cases( because it is an advantage to HFT firms to make it so ) and stop-loss orders will only provide limited protection. There is stop-limit orders( which allow you to specify a price limit that is acceptable ) on some markets and as far as I know InteractiveBrokers provide a guaranteed stop-loss fill( For a price of course ) that could be worth looking at, personally I dont use IB.  I hope this answer provides some helpful information, and generally speaking, super-short term investing is for algorithms. "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." When using the Stochastic Indicator your basic aim is to buy (go long) when the stochastic becomes oversold (goes below 20%) and then the %K line crosses above the %D line at a market low, and to sell (go short) when the stochastic becomes overbought (goes above 80%) and then the %K line crosses below the %D line at a market high. Other indicators or candlestick patters can also be used to further confirm the trade. Below is a chart of a trade I recently took on GUD.AX using the Slow Stochastic in combination with support and resistance levels as well as a candlestick pattern.  When I conducted my stock search on the evening of 28th July 2015, GUD was one of the results from the search that I particularly liked. The Slow Stochastic had just made a crossover in the oversold area just as the price was bouncing off its recent lows at the support line. But what I really like about this opportunity was that there was also a bullish reversal candle (a Hammer) at this short term market bottom. The high for the day was $8.34, so I placed a stop buy order to buy the stock tomorrow if the price opened or moved above this high of today. So I would only buy if the stock hit or moved above $8.35 during the next days trading. So if the stock opened and stayed below the previous day's high I would not buy the stock and my order would be canceled at the end of the day. This is very important because it stops you from getting into trades that don't go in the direction you want. If this happens then you could check the chart again after market close to see if it is still worthwhile to place a new order for the next day. On the 29th July 2015 the stock did open higher at $8.42 (which is where my order got executed) and closed at $8.46. So I ended up buying slightly above my target price but it did move higher on the day, so a successful entry overall. I had placed my initial stop loss at $8.09 (just below the low of the previous day of $8.10). If the trade had gone against me in the following days the most I would have lost was 1% of my total account capital. My target for this trade was $9.86 (just below the resistance line near $10), which would represent a 5% gain against my total account capital (or approx. 16.7% gain on the trade). So my win to loss ratio was 5:1. As you can see from the chart, the next day gapped up at the open and prices continued moving up strongly during the day. The next day was a slightly negative day, and then a few days later, on the 5th August 2015 my target price of $9.86 was reached (with a high of $9.88 for that day), so my order was closed for a total profit of 16.7% on the face value of the trade. However, as I bought on margin (using CFDs) my actual profit on the initial margin I had invested was 167%. My total time in the trade was 7 days, and I spent about an hour in the evening doing my searches and placing my orders, then less than 10 minutes managing the trade each evening after market close. The stock did go up a bit further after my profit target was reached, but the day after that the price started to fall as the price hit the resistance line and the Slow Stochastic did a crossover in the overbought area. Overall, this was a very ideal trade and I was very happy with it. Not all my trades reach my profit targets and I may get stopped out at a smaller profit or I might make a small loss (as I move my stops up as the price moves up). The key to successful trading over the long term is to keep you losses small and let your profits run (with my longer term trend trading I don't have profit targets and let my profits run until I get stopped out, but with my shorter term trading I do use a profit target usually 5 or 6 times the size of my initial stop). If you have an average win to average loss ratio of 3:1 or higher and have a success rate of 50% winners you will make money over the long term.