The problem with a cash account is that after you sell a ticker your money is now not free to trade until settlement which is (T+3 ) trade day plus 3 business days. You can not use unsettled funds in a cash account or it will be considered a "free-ride", after 1 or 2 "free-rides" your broker will put you on a 90 day restriction for that offense. For a frequent trader a margin account is the only way to go imo.