Why am I not getting a margin call when using all my available margin?

External question — Personal Finance Stack Exchange Author: Lyall Original post: https://money.stackexchange.com/questions/158816 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I'm in the UK and have several broker accounts, all of which have a 50% margin call requirement. I thought I understood how margin works and the reason for it. As I am a retail trader, I use 30:1 leverage. Using one small broker account example, which has a 50% margin stop-out, if I place a trade which uses all of my margin (or rather 95% of it) I am able to open the trade and keep the trade open, let it reach target and close it without any issues. Sometimes the trade is only open an hour, sometimes it's for 3 days. Even when my account drops down to negative available margin for a period of time, I have never had any issues or a margin call. Therefore I'm confused - at what point does a margin stop-out occur? Is it only at the end of the week? Is it only for trades above a certain value? The UK brokers I'm with say that margin requirement is 'constantly checked' but I've never seen any evidence. I wasn't even aware of the 50% requirement until I checked on the off-chance. OR does margin fundamentally work differently to how I am thinking, and rather than it being 50% of my available margin (account value) it's a 50% drop in position value, or something like that? I have: Read everything I can find about margin on Google Read all the information about margin calls, margin levels and margin requirements on my broker websites Read all related questions on this site But can't find an explanation. Any help appreciated, thanks!

External answer — Personal Finance Stack Exchange Author: Lyall Original post: https://money.stackexchange.com/a/158819 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I think I've figured it out. As an example: the margin requirement for a particular trade is £1000 which I have available as balance. this represents 5% of the total trade value (for a pair that has a 5% margin rate) this £1000 could also represent any proportion of my account balance, up to 100% if the trade goes badly and losses approach 50% of the staked margin (I.e. minus £500) then it would be a margin call. So the 50% applies as a loss vs the staked margin that was put forward as a 'deposit', not as an available amount as I was thinking. If your margin requirement for a trade is £7k then you would get a margin call if your losses reached -£3.5k, not when your available margin amount it is zero. The available margin figure is what's available for new trades, and isn't used for the margin call.