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Vietnam Stock Order Types: LO, MP, ATO, ATC Explained

The Vietnamese stock market has several order types: LO, MP, ATO, ATC, and MTL/MOK/MAK. We explain when to use each so you place orders correctly and avoid rejections.

Order TypesVietnam StocksTradingHOSE

Wrong order type — your order gets cancelled and you do not know why

Many new investors place an order, then see "no match" or "rejected" without knowing why. Usually it is because they chose the wrong order type for the session phase. Understanding Vietnam stock order types helps you place orders correctly and control price better.

LO — Limit Order

LO (Limit Order) is the most common: you set a specific price, and it only matches at that price or better.

  • Buy LO: only matches at your price or lower.
  • Sell LO: only matches at your price or higher.
  • Usable in both the continuous matching and periodic sessions.

LO gives you price control, but in exchange may not match if the price does not reach your level. This is similar to the limit vs market order concept in other markets.

MP — Market Order

MP (Market Price) matches immediately at the best available price, with no price input.

  • Prioritizes fast matching over price control.
  • Only usable in the continuous matching session.
  • Risk: for low-liquidity stocks, the matched price can deviate a lot (slippage).

ATO and ATC — periodic opening/closing orders

These are specific to the Vietnamese market:

  • ATO (At The Open): an order joining the periodic session that determines the opening price.
  • ATC (At The Close): an order joining the periodic session that determines the closing price.

Both take no price input, are prioritized over LO orders in the periodic session, and are cancelled if unmatched. The open/close prices are determined within the ceiling-floor band.

Market order variants (HNX)

On HNX there are also market-order variants:

  • MTL: matches what it can, the rest converts to LO.
  • MOK: match the entire order or cancel.
  • MAK: match partially or fully, the rest is cancelled.

Choosing an order type by goal

  • Want price control: use LO.
  • Want fast matching in the continuous session: use MP (accepting slippage).
  • Want to join the open/close price: use ATO/ATC in the right session.
  • Mind the session phase: MP and ATO/ATC only work in the right time window — placing them at the wrong time gets rejected.

Whatever the order type, the T+2 settlement rule still applies after matching.

Conclusion

The Vietnamese stock market has several order types: LO (limit, price control), MP (market, fast matching), ATO/ATC (periodic open/close), and the MTL/MOK/MAK variants on HNX. Choosing the right type by goal and session phase helps you place orders effectively and avoid rejections.

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