1) You would need the broker to allow you to use extreme leverage ( 1000:1 +)
2) You would need the broker to not widen the spread more then 10 pips prior to market close. (Fixed Spread Best)
3) You would simply need two accounts.

Here is what you would have to do.

1) Deposit the same amount of funds in both accounts. Say 2000 usd in both accounts.
2) Prior to the market closing (just seconds before) You place a buy in one account for 100% equity, and a sell in the other account for 100% equity.
3) The market would simply have to gap in either direction more then 10 pips (assuming you are using 1000). That would margin call one account, and cause the other account to recover what was lost in one of the two accounts. 100% of total account

10 pips more which it gaps!

That isn't theory it is indeed FACT! Other sites have pessimistic people who say things don't work, and don't even try it with a live account. Based on the conditions which I have mentioned above, and I won't mention which broker offers them, you can earn a ton of funds when the market gaps. The second the market gaps you trail stop the only account which has an open order