QUOTE:
A winning position could turn into a losing position if the Stop is taken by the software even if it occurred later in the day.
Sure, but I'm still having a hard time seeing why this is a problem - except
possibly for other "working" orders; but even in that case the effect on intraday buying power is minimal unless we're talking about an oversized position (say more than 20% of account equity) that drops 30% in one day. Even in the case, account equity drops
only 6%, but if you liquidated the position (stopped out), the cash is immediately available to enter new positions for margin accounts. And remember, this cash was
not available yesterday for other EOD orders.
At least with this example, I just convinced myself that exiting positions does not negatively affect intraday buying power for EOD orders. In the case of cash (IRA) accounts, exits can't influence other working orders at all because: 1) the cash in an exited position was not available when orders were entered anyway, and, 2) cash accounts usually* have to deal with the T+2 rule.
* This becomes more complicated when you consider "Portfolio Margin" (which in practice gives you more than 5:1 margin) or even "Limited Margin" option for qualifying cash accounts. (
Video here).
Will a simulation be perfect? No. That's not possible. But in my IRL experience of actually trading mechanical EOD systems - using MOO and Limit orders, I can offer that order fills almost always precisely match my simulations using
Wealth-Data. The only issue that I've had to deal with a handful of times are limit orders not being filled at the precise low of the day - and this is expected.
- I got off the "priority" discussion, and maybe it's because I haven't run into the use case, but I can't say that I've observed the problems with exits influencing entry priority, or vice-versa. Again, if you have a specific example (with numbers), I'd be glad to consider it.