How trade copiers work — architecture, latency and what to watch out for

Master/slave architecture explained

Trade copiers synchronize order flow across multiple MetaTrader accounts in real time. Modern architectures use high-performance local memory channels (Named Pipes, Shared Memory, ZMQ) or cloud WebSockets: 1. **Master Sender EA**: Captures OnTradeTransaction events when orders open, modify, or close. 2. **Broker Bridge / IPC Channel**: Serializes trade events into compact binary or JSON packets. 3. **Slave Receiver EA**: Deserializes event packets and executes matching orders locally in sub-5ms.

Lot scaling logic

Replicating exact lot sizes across different account balances leads to catastrophic risk mismatch. Copiers implement proportional lot scaling: $$\text{Slave Lot} = \text{Master Lot} \times \left( \frac{\text{Slave Equity}}{\text{Master Equity}} \right) \times \text{Multiplier}$$

Latency sources and how to minimise them

- **Network Latency**: Cross-broker execution adds round-trip time. Solution: Host Master and Slave EAs on co-located Equinix NY4/LD4 VPS servers. - **MQL Parsing Overhead**: Use binary DLL bridges instead of text-file polling. - **Slippage Tolerances**: Enforce max allowed slippage parameter to reject orders if price moves beyond tolerance during transmission.

Broker compatibility issues

Different brokers utilize varying symbol suffixes (EURUSD.pro vs EURUSD.ecn) and execution modes (Market vs Request execution). Copiers must map symbol aliases dynamically.