After-Hours Fixed-Price Trading vs After-Hours Odd-Lot Trading: Full Guide to Order Times, Units, and Matching Rules

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Many investors place stock orders after regular trading hours. After-hours trading in Taiwan is divided into two distinct methods with significantly different rules.

Core Differences

• After-Hours Fixed-Price Trading: Allows investors to buy or sell full lots of shares at that day’s closing price.
• After-Hours Odd-Lot Trading: Allows investors to buy or sell 1 to 999 shares through a separate call auction.

Understanding the differences between these two methods is the first step to choosing the right trading strategy.

Key Takeaways

• After-hours fixed-price trading and after-hours odd-lot trading are two different ways to trade stocks.
• Fixed-price trading only allows full lots (1,000 shares) at the day’s closing price.
• Odd-lot trading allows 1 to 999 shares with prices determined by bidding.
• If you want to buy or sell a full lot at the exact closing price, choose fixed-price trading.
• If you want to trade with small amounts or handle fractional shares, choose odd-lot trading.

Fixed-Price vs Odd-Lot After-Hours Trading: Quick Comparison

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To help investors quickly grasp the differences, the table below clearly shows the core distinctions between the two after-hours methods, covering everything from order windows to matching priority.

Quick Tip Both methods match at 14:30, but the rules are completely different. Fixed-price trading is like a group-buy at a set price; odd-lot trading is more like a mini auction.

Trading Hours

Fixed-price trading has a shorter order window from 14:00 to 14:30. Odd-lot trading opens earlier at 13:40 and also closes at 14:30. Both execute a single match at exactly 14:30.

Trading Unit

The trading unit is the most fundamental difference. Fixed-price trading is restricted to full lots of 1,000 shares. Odd-lot trading offers much greater flexibility, allowing any quantity from 1 to 999 shares.

Execution Price

In fixed-price trading, every trade executes at that stock’s official closing price of the day. It is a fixed price with no room for negotiation. If a stock has no closing price that day, fixed-price trading is suspended. In odd-lot trading, the price is determined by call auction from all submitted bids and offers, so the final price may be above, below, or equal to the closing price.

Matching Rules

Fixed-price matching order is completely random by computer and unrelated to submission time. Odd-lot matching is more complex: it first prioritizes higher buy bids and lower sell offers. When multiple orders are at the same price, it falls back to random computer selection, just like fixed-price trading.

After-Hours Fixed-Price Trading: Rules, Pros & Cons

Fixed-price trading provides a channel for investors to buy or sell full lots at the day’s closing price. The rules are straightforward, and understanding its mechanics and pros/cons helps investors decide if it fits their needs.

Order and Matching Time

Investors can place orders through their broker during the 30-minute window from 14:00 to 14:30. All orders submitted during this period are collected and matched once by the exchange at 14:30. Missing this window means no participation in that day’s fixed-price session.

Trading Unit and Price

This method has two core restrictions:

1. Trading Unit: Must be full lots (1,000 shares).
2. Execution Price: Fixed at that day’s official closing price—no custom pricing allowed.

This “one price for all” rule guarantees every executed order has exactly the same price, offering high price certainty.

Matching Rule: Random Computer Lottery

Matching order in fixed-price trading ignores submission time and price (since all prices are identical). When supply and demand are balanced, all valid orders execute. However, when total buy lots exceed sell lots (or vice versa), the exchange uses a random computer lottery to decide which orders fill. This means even if you place an order, execution is not guaranteed.

Advantages and Disadvantages

Advantages

• Clear pricing: Executes at the closing price—transparent, fixed, and free of unexpected slippage.
• React instantly to news: Many companies release earnings or major announcements after the close. This method lets investors act immediately at the closing price instead of waiting for the next day’s open.
• Convenient timing: The half-hour after regular hours is perfect for salaried workers who can’t watch the market during the day.

Disadvantages

• No execution guarantee: Random lottery means orders can fail when supply and demand are imbalanced—this is the biggest uncertainty.
• Lower liquidity: Far fewer participants than during regular hours; some less-popular stocks may have no counterpart orders.
• Unit restriction: Full-lot only, requiring higher capital—not suitable for small investors.

After-Hours Odd-Lot Trading: Rules, Pros & Cons

Odd-lot trading gives small investors an excellent opportunity to participate with lower capital. It allows buying/selling shares in amounts below a full lot, but the rules differ fundamentally from fixed-price trading.

Order and Matching Time

Investors can place orders from 13:40 to 14:30. All orders during this window are collected for processing.

Single Match Only The system performs one call auction at 14:30. All orders submitted within the window are decided at this moment.

Trading Unit and Price

Flexibility is the core feature:

• Trading Unit: Any quantity from 1 to 999 shares—perfect for capital-constrained investors.
• Execution Price: Not fixed at the closing price. It is determined by call auction from all bids and offers, settling at the price that maximizes traded volume. The final price can therefore be higher, lower, or equal to the day’s close.

Matching Rule: Price Priority

Odd-lot matching follows clear priority rules, very different from fixed-price random lottery.

1. Price priority: Higher buy bids and lower sell offers get priority.
2. Same-price random lottery: When multiple orders share the same price, the system uses random computer selection.

This means buyers willing to pay more or sellers willing to accept less have a higher chance of execution.

Advantages and Disadvantages

Advantages

• Low capital threshold: No need for a full lot’s worth of money—start investing with just a few thousand or even a few hundred TWD. Ideal for young workers and students.
• Portfolio flexibility: Easily buy small amounts of many different stocks for diversification.
• Access to high-priced shares: Allows ownership of expensive stocks like TSMC or Largan through fractional purchases.

Disadvantages

• Price uncertainty: Determined by auction—cannot lock in the closing price; you may pay more or receive less.
• Liquidity risk: Some less-traded stocks may lack sufficient counterpart orders in after-hours, causing failure to execute.
• No execution guarantee: Even with a competitive price, orders can fail if prices don’t cross or if you lose the same-price lottery.

After-Hours Trading Decision Guide: Which Should I Use?

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After learning the rules, many investors ask: “Which one should I actually use?” The answer depends entirely on your trading goal and capital situation. The following common scenarios will help you choose the best fit.

Scenario 1: Want to Trade a Full Lot at Closing Price

Situation: An office worker sees positive news about TSMC after the close and believes the stock will gap up tomorrow. He wants to buy one full lot immediately at today’s closing price to avoid next-day uncertainty.

The goal is clear: buy a full lot at the closing price.

Recommended Choice: Fixed-Price Trading

Fixed-price trading is the only method that meets this exact need. It is designed specifically for trading full lots at the day’s closing price. The investor can place a buy order for one lot of TSMC between 14:00 and 14:30, and the price will be locked at the official close.

Scenario 2: Want to Invest with Small Amounts

Situation: A recent graduate with limited monthly budget wants to start regular investing and gradually accumulate high-quality, high-priced stocks. He likes a stock priced several hundred TWD per share, but a full lot costs hundreds of thousands—too expensive.

His core need is to invest small amounts and he doesn’t mind if the price isn’t exactly the closing price.

Recommended Choice: Odd-Lot Trading

Odd-lot trading is the perfect companion for small investors. It allows buying just a few shares, dramatically lowering the entry barrier. This young investor can allocate a few thousand TWD each month to buy 5 or 10 shares of the target stock and easily start a long-term holding plan.

Scenario 3: Want to Sell Existing Odd Lots

Situation: A long-term holder receives stock dividends that leave him with 500 “odd-lot” shares. He wants to sell them to clean up his holdings and return to full lots for easier management.

His goal is simple: sell shares less than a full lot.

Recommended Choice: Odd-Lot Trading

Regular full-lot markets do not accept odd-lot sell orders, so after-hours odd-lot trading is the standard way to dispose of fractional shares. The investor can place a sell order for 500 shares between 13:40 and 14:30. To increase execution chances, he can reference the closing price or slightly undercut it.

Decision Keys: Unit and Price

In summary, choosing between the two methods boils down to two key questions. Answer them and the choice becomes obvious.

From this decision table:

• If you need a full lot and want to lock the closing price, choose fixed-price trading.
• If you need odd lots (buy or sell), the only option is odd-lot trading.

In conclusion, choosing fixed-price or odd-lot after-hours trading depends on two core investor needs. Simply clarify the following and you can easily pick the most suitable method to make your decisions more flexible.

• Do you want to trade a full lot or odd lot?
• Do you insist on executing at the closing price?

Answer these two questions and you’ll master the essence of after-hours trading, making the smartest choices for your portfolio.

FAQ

Here are the most common questions new investors have about after-hours trading, answered quickly.

Why didn’t my after-hours order execute?

After-hours trading never guarantees execution.

Fixed-Price: Uses random computer lottery. When total buy volume exceeds sell (or vice versa), some orders fail because they weren’t selected.

Odd-Lot: Price priority. If your bid/offer isn’t competitive (e.g., buy price too low), or you lose the same-price lottery, the order fails.

Can I cancel or modify an order after submission?

Yes. Until matching begins at 14:30, investors can freely cancel or modify submitted orders. Once matching starts, all orders are locked and cannot be changed.

Can all stocks be traded after hours?

No. Most listed stocks and ETFs are eligible for after-hours trading. However, stocks with special circumstances—such as new listings that day, trading method changes, or no closing price generated—are suspended from fixed-price trading. Always check eligibility before placing an order.