Market Price Protection (MPP)
Keep placing market orders even when your broker's API does not accept them — the system converts them to a protected limit order.
Market Price Protection (MPP) lets you keep placing market orders even when your broker's API does not accept them. AutoTrader Web converts a market order into a limit order at a price near the live price, with a small safety buffer so it still fills. You set it in Settings → General. There are four choices — None, Small, Normal and Aggressive — that control how big the buffer is. Normal suits most users.
What Market Protection does
When you place a market order (or a stop-loss market, also called SL-M order), AutoTrader Web can change it into a limit order (or a stop-loss limit order) at a price close to the current market price. This is called Market Price Protection (MPP).
You still trade like a market order — you do not pick the price yourself — but the order reaches your broker as a limit order with a small safety buffer, so it still fills quickly.
Why it is needed
To follow algo-trading rules, many brokers do not accept plain market orders through their trading API. Market Protection lets you keep placing market-style orders. The system converts them into a limit order at a price near the live price, with a small buffer so the order still gets filled.
Where to set it
Open Settings → General and choose your Market Protection (MPP) option.
The options
| Option | What it does |
|---|---|
| None | No change. Your market order is sent to the broker as-is. Use this only if your broker accepts market orders through its API. |
| Small | Converts to a limit order with a small buffer. The price stays closest to the market, but in a fast move the order may not fill. |
| Normal | Converts with a standard buffer. A good choice for most users. |
| Aggressive | Converts with a larger buffer, for a higher chance of filling in fast-moving or volatile markets. |
If you have not changed this setting, the system applies standard (Normal) protection.
How the buffer affects your order
- A bigger buffer sets the limit price a little further from the current price. Your order is more likely to fill, but it may fill at a slightly worse price.
- A smaller buffer keeps the price closer to the market, but in a fast move the order may not fill.
If your broker already protects market orders
Some brokers apply their own market protection. In that case AutoTrader Web does not convert the order again, so there is no double protection.
A note on rejections
In rare cases, the Aggressive option can set a price that falls outside the price range your broker allows for a limit order, and the broker then rejects the order. This was seen only during the early release of Market Protection and has not been seen since. If you ever face such a rejection, switch the setting to Normal.
Check what happened
Each conversion is recorded in your activity logs (Tools → Activity). Open the logs to see the limit price the system used for your order.
Next steps
Thanks for the feedback. Still stuck? Contact support.
Last updated 22 June 2026