· 2 min read
Copy trading explained: how master–child accounts work
Trade once in a master account and let child accounts follow. Here is exactly how quantities are calculated and what can go wrong.
Copy trading lets one master account drive many child accounts. When the master trades, each child places the same trade at its own size.
Copy on fill, not on order
The safest systems copy when the master order fills, not when it is placed. That way a limit order that never executes is never copied, and partial exits are mirrored exactly.
How child quantity is calculated
A common rule is:
child quantity = master quantity × multiplier, rounded down to whole lots
For example, with a NIFTY lot size of 75, a master buy of 150 and a child multiplier of 0.5 gives 75 — one lot. A multiplier of 0.25 would round down to zero lots, so that child is skipped rather than sent an invalid order.
Useful options
| Option | Why it helps |
|---|---|
| Max quantity per child | Caps exposure for smaller accounts |
| Reverse mode | Child takes the opposite side, e.g. for hedging |
| Pause | Stop copying without deleting the setup |
What should be mirrored
Entries are obvious — but exits, square-offs and kill-switch closes in the master must be copied too, or children are left holding positions the master has already closed.
Safety checks
Each child order should pass the child's own kill switch and risk limits. If a child is blocked, that child fails with a clear reason — the other children still get their orders. And avoid chains: an account that is a child in one setup should not be a master in another.
This article is for education only and is not investment, tax or legal advice.