Quote from ssrrkk:
I don't know, my experience with MM / microstructure is that markets can trend during the day which means you could have a whole day where the price has momentum pretty much in one direction -- and whatever price action rules you came up with will very likely bias your trades in one direction or the other. It would be too much of a coincidence if you were close to 50/50 day after day after day when the markets can go up 1-3% one day, and go down 1-3% another day... And in those types of trend days, I would expect your PL to fluctuate wildly. Still doesn't sound quite right. What's strange is your PL only fluctuates to the positive side...
Now I can guess that you will argue that at the micro scale it all balances out, but that is not really the case. Often you will see a series of large orders that take out one side of the quote repeatedly for several minutes. This kind of thing happens all the time. And there is really no way to anticipate marketable order flow like that: the reason the price jumps at those high volume bars is precisely because there were not enough orders on the book to keep the price stable so you can't really say the order book anticipates all of those price moves.
Now when I asked about the length of a trade, of course, I wasn't asking whether you imposed a time limit -- I was asking what the round-trip trade duration ended up to be with the limit orders. This will have huge consequences because if the trend negates the supposed spread you are earning, then your PL will suffer. Even if it averages out, it might take days or weeks, and your PL volatility will be huge, and your sharpe will take a big hit.
It still seems bizarre that you would give up this money making machine without even bothering to find out your own trading stats (win %, average winning trade, sharpe, etc) which I would think anyone would be curious if they wanted to fix their algo... Also, why not also think about hedging?