Trailing stop EAs that spam the server with modifications

[Fairman]

Trailing stop EAs that spam the server with modifications

A trailing stop EA that moves the stop on every tick can send a huge number of modification requests to the broker. On a fast day, that might be several per second. Most brokers don't like it, and some will warn you, throttle the account, or reject requests.

There's also a practical problem. Each modification is a request that takes time to process. If the EA sends a new one before the last one is confirmed, requests can pile up, and some fail. The stop on the server might end up lagging behind where the EA thinks it is.

The fix is to only modify when the change is meaningful. A minimum step, for example only moving the stop when it would move by at least a pip or two, cuts requests dramatically. A minimum time between modifications helps too. Checking that the new stop is actually different from the current one, after rounding to the symbol's tick size, avoids sending pointless requests that the broker might reject as 'no changes'.

It's also sensible to respect the broker's stop level. Trying to move the stop closer than allowed just generates errors.

Logging every modification, with time and result, helps you see whether the EA is behaving. If the log shows hundreds of modifications per trade, the step is too small.

[Fairman]

Some brokers have explicit limits on the number of modifications per order or per minute, often in the terms for automated trading. Exceeding them can get the account flagged. If you run an EA that trails tightly, reading those terms is a good idea, especially on prop accounts, where the firm might have its own rules about excessive messages to the server. A trail step of a pip or two usually keeps you well within any limits while still protecting most of the move in a trend. Some brokers send a warning email first, but others just start rejecting requests, which an EA might not handle well.

[Fairman]

Virtual trailing, where the EA tracks the trailing level itself and only sends a close order when price reaches it, avoids the modification problem entirely. The downside is the same as with any virtual stop: if the EA or connection fails, the position isn't protected by the trailing level. A combination works well for many people, with a server side stop at a wider level as a backup, and the tight trailing handled virtually. Then a disconnection only costs you the difference between the two. The backup stop should sit where the trade is clearly wrong, so a disconnection costs a known amount rather than an open ended one.

[FXS Prop Desk]

Most brokers prefer modifications at reasonable intervals, for example when the price has moved a minimum distance, such as 1 or 2 pips. Moving the stop on every tick creates heavy load and can lead to warnings or restrictions.

Adding a minimum step and a minimum time between modifications solves the problem without changing the trailing logic much. It also reduces the number of errors when the server is busy.

[Shadow Trader]

Here is something that catches people running tight trailing logic. A stop modification is a request to the trade server, same as sending a market order. It counts toward whatever request ceiling the broker applies.

A trail that updates every time price ticks one point can fire dozens of modifications a minute on a busy pair. Most of those move the stop by a fraction of a pip, which buys nothing, yet a broker that watches message volume may start rejecting, delaying or flagging the account.

There is a second cost. While modifications are queued, a genuinely new order or an urgent close can end up waiting behind them. The request that mattered gets processed late because a pile of trivial ones came first.

Trailing in steps, only when the stop would improve by a meaningful chunk of the spread or ATR, cuts traffic massively with almost no loss in protection. Some brokers also reject modifications that move the stop by less than a minimum distance, which turns tiny nudges into pure noise.

If a trailing routine is chatty, how often does it really need to update to do the job?

[Fairman]

Freeze levels are another broker setting that matters for trailing stops. The freeze level is a distance from the current price within which you can't modify orders. If your trailing stop is close to price and the freeze level is a few pips, modifications get rejected when price is near the stop. The EA should check the freeze level before sending a modification. If the freeze level is large on some instruments, a tight trailing stop might not be workable there at all, and a virtual exit might be the only option.

[Fairman]

How does the trail behave on a gap or a spike? If price jumps a lot in one tick, a trailing stop EA might send one large modification. That's fine. The problem comes if the spike reverses quickly and the stop is now very close to price, getting hit on the way back. Some EAs only trail on bar close or after price has held a level for a few seconds, which avoids reacting to brief spikes. It's a trade-off between locking in gains quickly and avoiding getting stopped on a spike that immediately reverses.