What Is an Expert Advisor? EAs in MetaTrader Explained

An Expert Advisor, or EA, is a program written in MetaQuotes' MQL language that runs inside a MetaTrader terminal and can open, modify and close orders without anyone at the keyboard. It is attached to a single chart, reacts to the price ticks arriving there, and applies the rules it was compiled with. An EA is a way of executing a strategy, not a strategy that works.

How it works

You compile the code, drop it on a chart, and the terminal calls it every time the market moves.

Price tick arrives on the chart
  → the EA's tick handler runs
  → rules are evaluated against price, indicators and open positions
  → an order is sent, stamped with a magic number
  → the broker's trade server accepts, rejects or requeues it

Three conditions must hold at once: the terminal is running and logged in, automated trading is permitted, and the broker accepts the request. Break one and the EA keeps running silently while placing nothing.

The critical detail is that an EA is client-side: it is a guest process inside a program running on a machine you own. The broker's server holds nothing of it except a stop loss or take profit already attached to an open position. Close the terminal and the code is simply not there any more, which is why an unattended strategy belongs on a VPS rather than a laptop that sleeps.

Each order the EA sends carries a magic number, the integer that lets several EAs share one account and still be read apart afterwards.

Why it matters

An EA removes hesitation, fatigue and the 3 a.m. problem. It also removes the judgement that would have switched it off. An EA has no idea that its edge stopped working; it will execute a broken rule set with exactly the same discipline it executed a good one.

Consistency of execution is the benefit on offer. Consistency is not profitability, and the gap between the two is where most automated money is lost. A strategy that looks flawless in the tester has usually been fitted to the sample it was tested on — see curve fitting — which is why a broker-synced account outranks any backtest report. The tester shows what the code did to history; the account shows what the code, the broker and the machine did to money together.

What the data shows

Automation is the default here, not a niche. Across the public accounts on ShowMyTrades with trading history (August 2026), the median autotrading share is 99%, 53.9% of accounts are more than 90% automated and 42.2% sit under 10%. Two clusters, almost nothing between them: an account here is run either entirely by code or entirely by hand.

Automation did not flatten the outcomes. The same population shows a median profit factor of 1.28, a median deepest drawdown of 9.7%, and a long left tail: 38.2% of accounts have been more than 20% under water, 17.6% more than 50%. Running a strategy by code changes who presses the button, not what the strategy is worth.

One boundary we hold to: we never estimate which commercial EA is running on an account. The same product installs with a different magic number on every account that buys it, so nothing in the broker feed identifies software, and a guess published as a fact would be worse than no answer.

Where you see it on ShowMyTrades

The account header carries a badge reading the automation split — for example 99% autotrading. It is not self-declared: a trade counts as automated when it arrives carrying a non-zero magic number, so the badge is a tally of the EA's own fingerprints on the order flow.

On an Expert Advisor connection, the Terminal & Open Charts module (Terminal on MT4, whose EA does not report a chart list) shows the environment the code lives in, including Auto trading reading Allowed or Blocked — the one switch that silently stops an otherwise healthy EA from placing anything. Below the tiles, the open charts table names the Expert Advisor loaded on each chart with its symbol, timeframe and indicators: what is running, rather than what is claimed. A password-only Direct Connection never touches your machine, so it reports none of this.

Per-strategy results live in the Breakdown Statistics module, under the By Magic Number tab, where each EA gets its own row of trades, profit and won/lost split. The Custom Analysis slideover narrows every statistic on the page to a single magic number, isolating one EA.

Common misunderstandings

• "The EA is the strategy." The EA is the executor. Two EAs implementing the same rules produce the same trades; the rules are what has value.
• "A great backtest means a great EA." It means the code and the history agree. That is the minimum requirement, not evidence.
• "Auto trading is on, so it is trading." Permission is not activity: with the AutoTrading button off the EA still loads and runs, it simply cannot send orders. Accounts go quiet this way for weeks.
• "It runs while my computer is off." It does not. Only the server-held stop loss and take profit survive a terminal that is down.

For the specific tells that separate a real automated record from a manufactured one: how to spot fake EA results.

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