All-or-None (AON) Order Singapore: Stopping SGX Trades From Filling in Annoying Fragments

An all-or-none (AON) order instructs a broker to execute the entire order quantity in a single transaction or not at all, preventing the partial fills that can otherwise leave an investor holding an odd, hard-to-manage quantity of shares.

Not financial advice. All figures for educational reference only. Data as at November 2026. Last updated: November 2026.

Key Takeaways

• An all-or-none order either fills completely in one go or does not execute at all — there is no partial fill outcome.
• AON orders are most useful for illiquid counters, structured trades, or situations where an investor specifically needs a round lot or a precise quantity, such as closing out a position exactly.
• Because AON orders are harder for the market to match, they often take longer to execute, or may not execute at all, compared to a standard order willing to accept partial fills.
• AON is distinct from a fill-or-kill (FOK) order: an AON order can wait in the queue for a complete match, while a FOK order is cancelled immediately if it cannot be filled in full right away.
• Not all Singapore retail brokers support AON order types natively; availability varies by platform, and traders should confirm with their broker before assuming the feature exists.

What Is an All-or-None (AON) Order?

Most stock orders on SGX are happy to be filled in pieces. If an investor places a standard order to buy 10,000 shares and only 6,000 shares are available at the desired price, the order typically fills 6,000 shares immediately and leaves the remaining 4,000 as an open order, or cancels the unfilled remainder, depending on the order’s time-in-force setting.

An all-or-none (AON) order changes that behaviour entirely: the broker and exchange will not execute any part of the order unless the entire quantity can be matched in a single transaction. If only a partial match is available, the order simply continues to wait (if it is a day or GTC-style AON order) rather than filling the available portion.

This matters most in two Singapore-specific situations. First, trading in illiquid counters — many small-cap and mid-cap SGX stocks trade thinly, and a partial fill can leave an investor with an awkward odd-lot position that is harder to resell. Second, in structured transactions such as a block trade, a crossing, or a large negotiated deal, where both sides need certainty that the full agreed quantity changes hands together, not in dribs and drabs across different prices and times.

How Does an All-or-None (AON) Order Work in Singapore?

When a Singapore investor places an AON order through a broker that supports it, the order sits in the broker’s or exchange’s order management system with an “all or none” flag. The matching engine will only execute it against a counter-order (or combination of counter-orders arriving simultaneously) that is large enough to fill the entire AON quantity at the specified price or better.

Because SGX’s central limit order book primarily matches based on price-time priority without inherently favouring “complete fills,” AON orders are more commonly handled through a broker’s internal order management rather than being a standard exchange-level order type available to every retail client. Institutional desks negotiating a block trade or crossing will often use AON logic bilaterally — essentially agreeing the full quantity and price directly, then printing it through SGX’s trade reporting mechanisms (such as a married deal or negotiated large trade) rather than relying on the open order book at all.

For retail investors, the practical workaround where a broker does not support true AON orders is to place a limit order sized to match available liquidity, and to break up trading manually into complete, intentional tranches rather than risking a partial, odd-lot fill.

an All-or-None (AON) Order Example

An investor holds exactly one board lot’s worth of shares — say 10,000 shares — in a thinly traded SGX-listed logistics company and wants to exit the entire position in one transaction to avoid being left with an awkward odd lot that is costly to sell separately. She places an all-or-none sell order for all 10,000 shares at S$0.85.

If a buyer only wants 6,000 shares at that price, the AON order does not execute at all — it keeps waiting. Three days later, a buyer looking to accumulate exactly one board lot at S$0.85 appears, and the full 10,000-share trade executes in one go. Had she used a standard order instead, she might have sold 6,000 shares on day one and been left holding an illiquid 4,000-share odd lot for weeks afterward.

Advantages of an All-or-None (AON) Order

• Avoids awkward odd-lot positions. Investors exit or enter with a clean, complete quantity rather than a fragmented leftover that is harder and more expensive to trade.
• Useful for structured or negotiated trades. Both counterparties in a large deal get certainty that the full agreed size transacts together.
• Reduces transaction costs from multiple partial fills. Some brokerage fee structures charge per transaction, so repeated partial fills can cost more in aggregate than one clean trade.
• Gives precise control over position size. Investors who need an exact quantity, for example to match a specific portfolio weighting, get exactly that or nothing.

Risks and Limitations

• The order may never fill. In illiquid counters, a matching counter-order of sufficient size may simply never appear, leaving the investor stuck holding (or failing to acquire) the position indefinitely.
• Missed opportunities during partial liquidity. If the market offers 90% of the desired quantity at a good price, an AON order forgoes that opportunity entirely rather than taking what is available.
• Limited broker support. Not every Singapore retail brokerage offers true AON functionality, so investors may need to manually monitor and manage trades instead.
• Price can move against the investor while waiting. The longer an AON order sits unfilled, the more exposed the investor is to the stock moving away from the desired entry or exit price.

All-or-None Order vs Fill-or-Kill Order vs Standard Limit Order

Source: General exchange order-type conventions as applied to SGX broker platforms, compiled November 2026.

The Bottom Line

For Singapore investors trading illiquid counters or specific lot quantities, an all-or-none order trades speed and certainty of execution for cleanliness of outcome — it either gives you the whole position in one shot or nothing at all, which can be exactly what you want when an odd-lot leftover would cause more hassle than it is worth.

Frequently Asked Questions

Related Terms

• Odd Lot Trading Singapore
• Board Lot (SGX) Singapore
• Iceberg Order Singapore
• Limit Order vs Market Order Singapore