4.1  Order Matching Method:

This method is executed on the stock trading system that matches buy and sell orders based on centralized order matching principles, prioritizing price and time.

The centralized order matching method includes:

• Periodic Order Matching: A trading method in which buy and sell orders are matched at a specified time on the trading system.

• Continuous Order Matching: A trading method in which buy and sell orders are matched immediately upon entering the trading system.

4.2  Put-Through Trading Method:

This method allows parties, via a trading member, to negotiate and agree on the transaction either on or off the trading system. Off-system agreements must be reported by a trading member to be recorded in the system.

5.1  Limit Order (LO Order):

• A Limit Order (LO) is a buy or sell order at a specified price or better — at or above the specified price for sells, and at or below the for buys.

• LO orders can be entered into the trading system during both the continuous and periodic order matching sessions.

• An LO order is valid from the time it is entered into the trading system until the end of the At-the-Close matching session or until canceled.

5.2  Market Orders:

Market orders can only be entered into the trading system during the continuous matching order session.

Types of Market Orders:

• Market Order (MP Order):is an order to buy at the lowest available sell price or to sell at the highest available buy price on the market. If there is no matching counter-order, the market order will be canceled immediately upon entry into the trading system. When matching counter-orders are available, the market order will be executed according to the specific rules applicable to each type of market order as follows:

• Market to Limit Order (MTL Order):Is an order in which unmatched volume is converted into a Limit Order (LO). For buy orders, this will be one tick above the last matched price, or the ceiling price if the last matched price is the ceiling. For sell orders, the LO will be at one price increment below the last matched price, or the floor price if the last matched price is the floor. Once converted, the LO must comply with all applicable rules and regulations regarding the amendment and cancellation of Limit Orders.

• Market – Fill or Kill Order (MOK Order): If the MOK order cannot be fully executed immediately, or it’s canceled by the trading system.

• Market – Fill and Kill Order (MAK Order):The MAK order can be fully or partially filled; the rest is canceled immediately.

5.3  At-the-Open Order (ATO Order)

An ATO order is a buy or sell order where the order price is recorded by the trading system based on the following principles:
If only ATO orders are present in the order book:

• The price will be the reference price if only buy ATO or only sell ATO orders are available, or if total buy volume equals total sell volume.

Price Priority:

• Buy orders with higher prices are given execution priority.
• Sell orders with lower prices are given execution priority.

Time Priority: 

In case buy or sell orders have the same price, the order entered into the trading system first will be prioritized to be executed first.

7.1  Periodic Matching Price: 
a. The matching price is the price at which the trading volume is the highest, and all buy orders with higher prices and sell orders with lower prices must be fully executed. 

b. If multiple prices satisfy point a, the selected price will be the one where all orders of one side are fully executed, and orders from the opposite side are fully or partially executed. 

c. If multiple prices satisfy point b, the selected price will be the one closest to the last executed price under the matching method. 

d. If no price satisfies point b, the selected price will be the one satisfying point a and is closest or equal to the last executed price under the matching method.

7.2  Continuous Matching Price: The execution price is the price of the matching order waiting on the order book.

Amendments or cancellations of matching orders are only effective for orders that have not been executed or for the remaining unexecuted portion of the order.

• In the opening periodic matching order session, amendments or cancellations of LO and ATO orders are not allowed.

• In the continuous matching order session, LO orders can be amended price and volume (amending both price and volume at the same time is not allowed) and can be cancelled during trading hours. The priority of the order after amendment is determined as follows:

• The order's priority remains unchanged if only the volume is reduced.

• The order's priority will be recalculated from the time the modified order is entered into the system for cases of increasing volume or changing the price.

• In the closing periodic matching session, modifying or cancelling LO or ATC orders is not allowed, including LO orders transferred from the continuous matching session.

• In the post-market session, orders from the post-market session cannot be amended or cancelled.

• Put-through transactions do not apply on the first trading day of listed stocks, ETF certificates, closed-end fund certificates, listed covered warrants, and securities that have been suspended or halted for trading continuously for 25 trading days, until a price is established from the results of the matching of even-lot orders.

• Put-through transactions of listed stocks, ETF certificates, closed-end fund certificates, and listed covered warrants must comply with regulations regarding the daily trading band.

• Put-through transactions are conducted based on the principle that the seller or buyer enters the trade order into the system, and the other party confirms the put-through transaction.

Executed Put-through transactions cannot be amended or cancelled.

Foreign investors must comply with Vietnamese laws related to trading stocks. 

The volume of stocks and closed-end fund certificates that foreign investors are still allowed to purchase is calculated based on the following principles:

11.1  For Matching Transactions:

• The buying volume of stocks or closed-end fund certificates of foreign investors is deducted from the volume they are allowed to buy immediately after the buy order is entered into the system.

• The selling volume of stocks or closed-end fund certificates of foreign investors is added to the volume they are allowed to buy after the securities transaction is settled.

• Buy orders for stocks or closed-end fund certificates from foreign investors will not be accepted if the remaining volume they are allowed to buy is less than the volume of the order.

• If the buy order for stocks or closed-end fund certificates from foreign investors is reduced in volume, the remaining volume they are allowed to buy will increase by the reduced volume of the order immediately after the order modification is entered into the system.

• If the buy order for stocks or closed-end fund certificates from foreign investors increases in volume, the remaining volume they are allowed to buy will decrease by the increased volume immediately after the order modification is entered into the system. If the remaining volume is less than the increased volume, the trading system will not accept the modified order.

• If the buy order for stocks or closed-end fund certificates from foreign investors is canceled by the investor or the trading system, the remaining volume they are allowed to buy will increase by the volume that was canceled.

11.2  For Put-through Transactions:

• The volume of stocks or closed-end fund certificates that foreign investors are allowed to buy will be reduced immediately after the buyer's put-through order is entered into the system if the transaction is between a foreign investor buying and a domestic investor selling.

• If a foreign investor cancels the put-through transaction order with a domestic investor, the volume of stocks or closed-end fund certificates that the foreign investor is allowed to buy will increase immediately after the cancellation order is entered into the system.

• The volume of stocks or closed-end fund certificates that foreign investors are allowed to buy will increase immediately after the transaction settlement if the transaction is between a foreign investor selling and a domestic investor buying.

12.1  The ceiling price and floor price for the trading day of stocks, closed-end fund certificates, and ETF certificates are rounded down for the ceiling price and rounded up for the floor price according to the specified price unit.

12.2  The ceiling price and floor price are determined as follows:

• For stocks, closed-end fund certificates, and ETF certificates:
  • Ceiling price = Reference price + (Reference price × price limit)
  • Floor price = Reference price - (Reference price × price limit)
• For covered warrants:
  • Ceiling price = Covered warrant reference price + (Ceiling price of the underlying stock - Reference price of the underlying stock) × 1/Conversion ratio
  • Floor price = Covered warrant reference price - (Reference price of the underlying stock - Floor price of the underlying stock) × 1/Conversion ratio

If the floor price of the covered warrant is less than or equal to zero (0), the floor price will be the smallest quoted price unit.

12.3  If the ceiling price or floor price of stocks, closed-end fund certificates, or ETF certificates is determined to be equal to the reference price:

• Adjusted ceiling price = Reference price + 1 quoted price unit
• Adjusted floor price = Reference price - 1 quoted price unit

12.4  If the floor price after the adjustment above is less than or equal to zero (0), the floor price will be adjusted to the reference price.

12.5  After calculation, if the reference price is equal to the quoted price unit, the price limit will be re-determined as follows:

• Adjusted ceiling price = Reference price + 1 quoted price unit
• Adjusted floor price = Reference price - 1 quoted price unit
  

13.1  The determination of the price for newly listed stocks, closed-end fund certificates, ETF certificates, and covered warrants on the first trading day is as follows: 

a) The reference price applied to newly listed stocks, closed-end fund certificates, and ETF certificates on the first trading day is proposed by the listing organization. For call warrants based on underlying stocks, the reference price on the first trading day is determined as follows:

Reference price of the call warrant = Issue price of the call warrant × (Reference price of the underlying stock on the first trading day of the warrant / Reference price of the underlying stock on the day of the warrant's issuance announcement) × (Conversion ratio on the day of the warrant's issuance announcement / Conversion ratio on the first trading day of the warrant).

b) In the event that the closing price cannot be determined within three consecutive trading days from the first trading day of stocks, closed-end fund certificates, or ETF certificates to be used as the reference price for the next trading day, the listing organization must issue a written request to confirm the reference price, which must be submitted to the stock exchange by 4:30 PM on the third day when the reference price cannot be determined.

13.2  The reference price of stocks, closed-end fund certificates, and ETF certificates on the trading day is the closing price of the nearest previous trading day.

13.3  The reference price of stocks, closed-end fund certificates, ETF certificates, and covered warrants that have been suspended or halted for trading for 25 consecutive trading days or more, when trading resumes, will be determined by the stock exchange.

13.4  If the securities transaction does not include dividends or associated rights, the reference price on the ex-rights date will be determined based on the closing price of the nearest previous trading day adjusted by the dividend or the value of the associated rights, except in the following cases:

a) The company issues additional stocks or closed-end fund certificates at a price equal to or higher than the closing price of the preceding trading day after adjusting for other rights (if any).

b) The company pays cash dividends with an amount equal to or greater than the stock closing price on the preceding trading day.

c) The company issues stock dividends or bonus stock to existing shareholders.

13.5  In the case of stock splits or consolidations, the reference price on the resumption trading day will be determined based on the closing price of the last trading day before the split or consolidation, adjusted according to the split or consolidation ratio.

14.1  Odd lot trading is conducted through the centralized matching method and the agreement trading method on the trading system.

14.2  Investors are only allowed to place LO orders for odd lot transactions and must comply with the same rules for modifying or canceling LO orders as for even lot transactions.

14.3  The unit for odd lot transactions is 1 stock, 1 fund certificate, or 1 covered warrant.

14.4  Transaction Price:

a) The price of the odd lot transaction must comply with the rules for transaction prices similar to those of even lot transactions.

b) Odd lot transactions cannot be used to determine the reference price or the index calculation price.
14.5  Odd lot transactions for newly listed stocks, fund certificates, or covered warrants, or for those resumed after being suspended or halted for 25 or more consecutive trading days, cannot be entered into the trading system until the price has been established from the results of even lot matching transactions.