Bid-Ask Spread Singapore
The Hidden Cost Every SGX Trade Pays Before You Even Factor in Brokerage Fees
The bid-ask spread is the difference between the highest price a buyer is willing to pay (the bid) and the lowest price a seller is willing to accept (the ask) for a stock, representing an implicit trading cost that widens for less liquid SGX counters.
Not financial advice. All figures for educational reference only. Last updated: October 2026.
Key Takeaways
- The bid-ask spread is the gap between the best available buying price (bid) and selling price (ask) for a stock at any given moment.
- Highly liquid SGX blue chips, like the major banks, typically have narrow spreads of just one or a few price ticks, while thinly-traded small caps and penny stocks often have much wider spreads.
- A wide bid-ask spread is an implicit trading cost — if you buy at the ask and immediately sell at the bid, you lose the spread amount even before any brokerage commission.
- SGX uses a minimum price variation (tick size) system, which sets the smallest allowable price increment between the bid and ask depending on a stock’s price range.
- Using a limit order instead of a market order can help control how much of the spread you pay when entering or exiting a position, especially for less liquid counters.
What Is the Bid-Ask Spread?
At any given moment during trading hours, a stock has two key prices visible on the order book: the bid, which is the highest price any buyer currently has an order in to pay, and the ask (also called the offer), which is the lowest price any seller currently has an order in to accept. The bid-ask spread is simply the difference between these two numbers.
This spread exists because buyers want to pay as little as possible and sellers want to receive as much as possible — the market only executes a trade when a buyer and seller agree to meet at the same price, either because a new order crosses the existing spread or because the bid and ask prices move to match.
The size of the spread is heavily influenced by liquidity — how many buyers and sellers are actively trading a stock. Highly liquid stocks, with many participants constantly placing orders, tend to have narrow spreads because competition among buyers and sellers naturally compresses the gap. Illiquid stocks, with few active traders, often have wide spreads because there’s less competition to narrow the gap between what buyers are willing to pay and what sellers are willing to accept.
How Does It Work in Singapore?
On SGX, the bid-ask spread is directly shaped by the exchange’s minimum price variation, or tick size, rules, which set the smallest allowable increment a price can move depending on which price band the stock falls into — generally, lower-priced stocks have smaller tick sizes than higher-priced stocks, though the exact increments are set by SGX and can be revised over time.
For actively traded SGX blue chips like the major local banks or large-cap REITs, the bid-ask spread is typically just one or two ticks — a very small percentage of the share price. For thinly-traded small-cap or penny stocks, however, the spread can represent a much larger percentage of the share price, sometimes several percent or more, which meaningfully affects the real cost of entering and exiting a position.
| Stock Type | Typical Liquidity | Typical Spread (as % of price) |
|---|---|---|
| Large-cap SGX blue chip | High | Very narrow (often <0.1%) |
| Mid-cap S-REIT | Moderate | Narrow to moderate |
| Small-cap/penny stock | Low | Wide, can exceed 1-5% |
Figures are illustrative generalisations, not fixed values — actual spreads fluctuate throughout the trading day based on real-time order flow.
Worked Example
A Singapore investor looks at the order book for a thinly-traded small-cap SGX stock and sees a best bid of S$0.48 and a best ask of S$0.50 — a spread of S$0.02, or about 4% of the share price. If she buys 1,000 shares at the ask price of S$0.50 (costing S$500) and immediately needed to sell, the best available bid is still S$0.48, meaning she’d only receive S$480 — a S$20 loss purely from crossing the spread, before any brokerage commission.
Compare this to a large-cap SGX bank stock where the bid might be S$42.98 and the ask S$43.00 — a spread of just S$0.02, but only about 0.05% of the share price. Buying and immediately selling 1,000 shares there would cost only about S$20 on a S$43,000 position, a far smaller percentage drag than the penny stock example.
Advantages
Understanding spreads helps you choose better entry points. Knowing how to read the bid-ask spread lets you use limit orders strategically to avoid overpaying when entering a position in a less liquid stock.
Tight spreads on liquid stocks reduce trading costs. Sticking to well-traded, liquid SGX counters where spreads are narrow keeps the implicit cost of trading minimal.
Spread width is a useful liquidity signal. A consistently wide spread is a quick, visible way to gauge how easily you’ll be able to enter or exit a position without moving the price against yourself.
Risks and Limitations
Wide spreads are an invisible cost many investors overlook. Unlike a brokerage commission, the spread doesn’t appear as a line-item fee, but it reduces your effective return just as surely, especially for frequent traders of illiquid stocks.
Spreads can widen suddenly during volatility. During market stress or around major news events, even normally liquid stocks can see their spreads widen temporarily as market participants pull back their orders.
Market orders are especially vulnerable to wide spreads. Using a market order in an illiquid stock means accepting whatever the current ask (when buying) or bid (when selling) happens to be, which can be far from the ‘last traded price’ you saw before placing the order.
Large orders can move the spread against you. In a thin order book, a large buy or sell order can exhaust the available liquidity at the best price, forcing the remaining portion of your order to fill at progressively worse prices.
Comparison Table
| Order Type | Interaction With the Spread | Best Used When |
|---|---|---|
| Market order | Crosses the spread immediately, accepting current bid/ask | Stock is highly liquid, speed matters most |
| Limit order | Lets you set your own price within or outside the spread | Stock is illiquid, price control matters most |
The Bottom Line
For Singapore investors, the bid-ask spread is a trading cost that’s easy to overlook because it doesn’t show up as a separate fee — but for thinly-traded SGX counters, it can meaningfully erode returns. Favouring liquid stocks and using limit orders on less liquid ones are two practical ways to keep this hidden cost under control.