Quote from Random.Capital:
What happens when a liquidity hole opens up and it gaps way way past the stop?
Or more exactly - how does that risk get quantified and factored into the OP's original question?
I already explained it in the other thread by the same OP with the same topic. Basically you figure your % risk you want to accept per trade. In a $100K acct lets say that is 1%...so $1000.
If for example the stock you are buying is $100 and you decide your stop loss is at $98. There is a $2 difference per share. That is your RISK PER SHARE. You then are "allowed" to buy 500 shares max for a total RISK PER TRADE.
However, as you mentioned price could gap down to $92 for a $4000 loss. Luckily this should not happen often. This is more common in highly volatile stocks and stocks priced under $10. The other thing to consider is that if it is a thinly traded stock then you could gap down simply because there are a lack of enough buyers for you to sell to when you want to liquidate your position.
There are a few things you can do to HELP prevent this RISK of gap losses. 1) adjust stops wider for more volatile stocks. 2) only buy stocks or ETFs > $10 or so. 3) Only trade stocks or ETFs that are traded at least 1,000,000 shares a day. The other thing I do is only trade a MAX number of shares that can be liquidated in 30 sec or less. To figure this I know there are 780 30 sec time periods in a trading day of 6.5 hrs. So I will only trade a maximum of the average vol of shares/780. If average volume of shares traded in a day is 390,000 then I will only allow myself a MAX of 500 shares to trade in that stock/ETF.
These rules will NOT work all the times and you will get caught with gap losses past your stop loss at some point. The only other thing you can do is limit this damage by risking less per trade as I described above (1% or less is a good rule of thumb until you have data of about 100-300 trades to STATISTICALLY determine you optimal risk to meet your goals).
Realize that nothing is life is 100%. Gap losers is just something that has to be factored in to your R (risk), Expectancy of your system, and Position Sizing of your system. Your best option is to combine all of the rules I have described above and if you think you would risk 1% on a trade risk more like 0.8% instead and you should be fine.
Good Luck