You sell the last unit on Shopee. Ten minutes later, a customer buys the same unit on your own website. Now you’re writing an apology and cancelling an order. Here’s why that keeps happening, what it costs, and how to stop it.

Why does selling on more marketplaces raise the risk of overselling?

Southeast Asia’s platform e-commerce sales grew 22.8% to US$157.6 billion in 2025, so each extra channel adds more orders drawing on the same stock. Momentum Works reports that this was the fastest growth in four years, at 22.8% (Momentum Works, 2026), and more orders mean more chances for two channels to sell the same last item.

Overselling happens when every channel keeps its own count. Your website thinks you have three left, Shopee thinks you have three left, and a sale on one doesn’t reduce the other until someone updates it by hand. A shop selling on its own website and two marketplaces is really running three separate counts of one shelf, and the gap between them widens just as sales improve.

Southeast Asia’s platform e-commerce sales grew 22.8% to US$157.6 billion in 2025, so more orders now compete for the same stock (Momentum Works, 2026).

How do small retailers usually find out they’re out of stock?

Nearly one in four small retailers only learn an item is out of stock when a customer tries to buy it. That finding comes from Global Payments’ 2025 Retail Inventory Report, a survey of 200 small retailers (Global Payments, 2025). The same report found that about a third say their systems are disconnected or glitchy, which is exactly how a stock-out stays hidden until checkout.

For you, the warning rarely arrives as a low-stock alert. It shows up as a cancelled order, a refund request or an unhappy review, and by then the sale is already gone.

Nearly one in four small retailers only learn an item is out of stock when a customer tries to buy it (Global Payments, 2025).

How much do stock-outs and overstocks cost retailers worldwide?

Global retail inventory distortion, meaning overstocks plus out-of-stocks, costs about US$1.7 trillion a year, or 6.2% of worldwide retail sales. That’s IHL Group’s latest estimate, reported by Retail Insight Network in August 2026, and it works out to roughly US$6 of every US$100 of retail sales (Retail Insight Network, 2026).

It’s a global figure rather than a number for your shop. What it shows is that the problem isn’t a small-business quirk. It’s a built-in cost of selling physical goods, and it grows when stock is spread across more than one place.

Global retail inventory distortion costs about US$1.7 trillion a year, or 6.2% of worldwide retail sales, according to IHL Group research reported in 2026.

Are out-of-stocks or overstocks the bigger problem?

Out-of-stocks cause about 65.6% of inventory distortion, almost double the 34.4% caused by overstocks. In practice, two out of every three distortion dollars come from not having stock when a customer wants it (Retail Insight Network, 2026).

For a small seller that points to a clear priority: protect the sales you could already have made before you worry about trimming extra stock. The table below puts the main figures side by side.

How many customers never come back after a stock-out?

16% of small retailers say up to half of their customers never return after a shortage. That comes from Global Payments’ 2025 survey of 200 small retailers (Global Payments, 2025), and it’s self-reported, so treat it as a warning sign rather than an exact measure of your own shop.

The pattern is easy to picture. A customer who hits a “sold out” page or receives a cancellation email has little reason to wait for you when a competitor has the item ready to ship.

How much of a small retailer’s money is tied up in stock?

Inventory ties up 20% to 60% of business capital for most small retailers, so every miscount is expensive. Global Payments’ 2025 report puts that range at 20% to 60% of capital (Global Payments, 2025).

When a fifth to well over half of your money sits on shelves, a wrong count hurts in both directions. Count too low and you reorder stock you already have. Count too high and you sell items you can’t ship. Either way, cash that could be working elsewhere gets stuck or wasted.

Inventory ties up 20% to 60% of business capital for most small retailers, so every miscount is expensive (Global Payments, 2025).

How many small retailers still count stock by hand?

Over half of small retailers still rely on manual counts to track inventory. Nearly half also say they want real-time inventory data (Global Payments, 2025), so the gap between what owners want and what they actually use is wide.

Manual counts aren’t wrong, just slow. A spreadsheet is only as current as the last time someone typed into it, and it can’t tell Shopee that your website just sold the last unit.

What does it cost to rush a missing item back into stock?

A single rush to replace a missing item can cost up to US$150. Global Payments’ 2025 report cites up to US$150 per rushed item (Global Payments, 2025), and that’s before you count the lost sale or the customer’s trust.

Spread over a handful of oversold orders a month, that adds up fast, and none of it grows your sales.

What’s the practical way to stop overselling?

Keep one central stock count that every sales channel reads from and updates, so a sale on one channel immediately lowers what the others can sell. Here’s the practical way to think about it: your stock has one home, and your website, Shopee and Lazada are just windows onto it. That matters because about a third of small retailers report disconnected or glitchy systems, and nearly half want real-time inventory data (Global Payments, 2025).

1. List every channel that sells the same product: your website, Shopee, Lazada and any physical shop.
2. Choose one place to hold the master count, and treat every channel as a window that reads from it and updates it.
3. Make sure every sale, cancellation and return updates that count straight away, not at the end of the day.
4. Keep a small safety buffer on fast sellers, so a delay of a few minutes can’t oversell your last unit.

If you’d rather not build that yourself, Asalta Inventory is one option: it runs multichannel stock sync across warehouses and marketplaces so your stores, website and marketplaces share a single count. Whatever tool you pick, check that it supports the exact channels you sell on before you commit.

Key Takeaways

• 65.6% of the damage is out-of-stocks: protecting sales you could already make comes before trimming extra stock.
• Nearly 1 in 4 retailers find out at checkout: a stock-out that nobody sees is a sale you lose twice, once when it fails and once when the customer leaves.
• 20% to 60% of capital sits in stock: every miscount ties up or wastes real cash.
• One central count beats three separate ones: your website, Shopee and Lazada should all read from and update the same stock.