I've been backtesting and optimizing a simple strategy that averages a 0.55% gain per trade. It'll be an automated system making about 10 trades per day in 200-500 share blocks in mid-priced stocks with $0.01 spreads. Is a 0.55% gain per trade from backtesting good, mediocre, or useless in the real world? The backtesting doesn't account for slippage and the strategy mostly takes place at the open when things are moving quickly. What should i expect? I've read that $.07 of negative slippage on $50 stocks and $.03 for $20 stocks are average for filling market orders of this type at this time. I'll eventually experiment with limit orders but I'd rather use market orders to make sure that every possible trade is entered in case the hardest-to-enter trades are the most profitable. If $.07/.03 is the worst-case scenario, the strategy would still be decent if it lost that much on the fill and maybe half that much on the exit. Is this a reasonable expectation?