Stock / forex trading 100s of transactions per day - how is the margin calculated?

External question — Personal Finance Stack Exchange Author: delica Original post: https://money.stackexchange.com/questions/93745 License: CC BY-SA 3.0 — https://creativecommons.org/licenses/by-sa/3.0/ Adaptation: HTML converted to plain text; contact email addresses removed. Let's say I have 10k USD in my margin account. I place 100 round trip orders in a single day, each worth 2000 USD (999 USD buy order and 1001 USD sell order). How much margin did I use at the end of the day? Can I do as many 2000 USD round-trips a day as I like? I am trying to understand how I can do frequent day trading without running into an issue with unsettled funds. I am interested in an answer both relating to stock and forex trading, and any other instrument that settles instantly or otherwise allows me to trade 100s of round-trips each day.

External answer — Personal Finance Stack Exchange Author: Stan Kurdziel Original post: https://money.stackexchange.com/a/93825 License: CC BY-SA 3.0 — https://creativecommons.org/licenses/by-sa/3.0/ Adaptation: HTML converted to plain text; contact email addresses removed. It depends not only on the particular country (and therefore regulating organization), but also the particular broker and even the type of account you have at that broker and probably even your trading patterns over the past week or longer. If you are in the US, start with the FINRA margin rules and then check with your broker. They may have an even more extensive set of guidelines, for instance TDAmeritrade's Margin Handbook If I had to guess, I would guess that you are likely to run into problems making hundreds of round trips trades per day, but really if you are paying commissions on all those trades and you aren't trying to risk more than your allowed margin at any given time, then there must be brokers who would love to help you.