So I got this deal (I don't want to talk about where and how) where I trade equities commission free (regulatory and exchange fees still apply) in exchange for a cut of the profits. Some more details: Fast manual order entry with level 2 Programmable interface Intraday capital practically unconstrained I have some acumen in programming and quant finance/machine learning Access to other financial products (futures, currencies..) Constraints: Strictly intraday Amount of risk (daily stoploss) very tight and dependent on consistency of results. E.g. less than 20% losing days, with losing days not much larger than winning days. Programmable interface slow, no co-location. Fast enough to beat any human, slower than anything else. Are there opportunities here for outsized profits? E.g. on SPY if I trade with resting orders most of the time, exchange plus regulatory fees can balance out to zero, net = gross. Btw I don't think automatization is the answer, as I am too slow for simple HFT strategies/arbitrage. And slower automatic strategies are not consistent enough I believe.