High Trading Volume. Why Is It Still Hard to Sell?

First, a question. Both stocks in this exercise are fictional.

Sep. 14, 2026 · Real market dataThe KRX After-Hours Market Opens

On September 14, 2026, the Korea Exchange (KRX) launched its after-hours marketTrading outside the regular session. KRX began offering a 4:00–8:00 p.m. session on September 14, 2026., running from 4:00 to 8:00 p.m. Trades worth KRW 1.8177tn were executed over four hours, and at least one trade took place in 2,413 stocks—96% of the eligible names.

That same day, volatility interruptionsA stock-specific mechanism that switches trading to a two-minute call auction when prices move sharply. Usually abbreviated VI in Korea. (VI) were triggered 1,637 times, roughly four times the 400 recorded during regular trading. Both totals count simultaneous static and dynamic interruptions twice. Counting each overlapping event once gives 1,112 after hours versus 391 in the regular session. KRX said the trigger thresholds were the same in both sessions.

KRX judged price formation across the market to be generally stable. But some small- and mid-cap stocks swung sharply. Hanwha Galleria climbed to KRW 3,070 around 4:20 p.m., then stood at KRW 2,635 by 7:50 p.m. The exchange attributed temporary liquidity shortages in some names to limited participation on the new market's first day. A thin order book means that even a small order can move the price.

If KRW 1.8tn Changed Hands,
Why Did Prices Jump?

Trading value and trading volume add up completed trades. They cannot tell you how many buyers are waiting to take your shares at this moment. For that, you need the order book. Stock B in our quiz had plenty of trades earlier in the day but little bid depth now.

And while KRW 1.8tn sounds substantial, it was only about 6.6% of total KRX trading value that day.

That money was spread across more than 2,400 stocks and four hours. At the level of a single stock at a particular moment, the available orders could still have been thin.

Open the order book and the answer becomes clearer.

Every Share Traded Has a Buyer and a Seller

Trading volumeThe number of shares exchanged in completed trades. Every share sold is also a share bought. is the number of shares that changed hands. If someone sells 100 shares, someone else has bought those same 100 shares.

That number does not tell us who was more eager to trade. High volume only means that a large number of shares changed hands between buyers and sellers.

How to Read an Order Book

Unfilled orders sit in the order bookAn order offering to buy or sell at a stated price. It has not yet been executed.. Sell orders (asks) appear above the market, and buy orders (bids) below it. The number of shares waiting at each price level is known as order-book depthThe quantity of shares resting at each price level. It shrinks when orders execute or are canceled..

The gap between those prices is the bid–ask spreadThe difference between the best ask and best bid. A narrower spread generally makes trading easier.. Prices move in set increments called tick sizesThe minimum permitted price increment. Since a 2023 rule change, it is KRW 10 for shares priced KRW 10,000–20,000 and KRW 100 for KRW 100,000–200,000.. For shares priced around KRW 10,000, each tick is KRW 10. In actively traded stocks, the spread may be only one or two ticks. Stock B's spread is ten ticks wide.

The difference between the price you saw when placing an order and your actual average fill is called slippageThe gap between the price seen when an order is placed and the actual average fill. It generally grows with order size and thinner bids.. It can arise when a large order sweeps multiple price levels or when quotes change while the order is being placed. The ability to buy or sell promptly without moving the price much is called liquidityThe ability to buy or sell quickly without substantially moving the price. Volume alone cannot measure it.. Deeper resting orders generally mean better immediate liquidity.

When You Cannot Sell—even for a Moment

If prices move too quickly, an exchange may slow or suspend trading. Such safeguards are intended to limit the speed of disorderly moves, not to prevent declines. Prices may fall further after trading resumes. While a halt or call auction is in effect, you cannot necessarily sell at the moment you want. The 1,637 VI activations on the first after-hours day are one example.

A VI activation puts the affected stock into a two-minute call auctionA system that collects orders for a set period and matches them at one price. Used at the open, at the close, and during volatility interruptions., with orders collected and executed together at a single price. You cannot obtain an immediate execution during those two minutes. From September 14, 2026, Nextrade (NXT) likewise switched to two-minute call auctions when VI was triggered.

A stock at its daily lower price limit cannot trade at a lower price that day. Sell orders accumulate at the limit, but they execute only when buy orders arrive. After heavy selling through a foreign securities firm's brokerage accounts in April 2023, Seoul City Gas, Daesung Holdings and Sunkwang hit the lower limit four sessions in a row. Trading remained sparse even on the morning of the fourth day. When there are sellers but no willing buyers, reported volume can actually be very low.

High-volume rankings grab attention. But the numbers worth checking immediately before selling are different.

For Past Activity, Look at Trading Value

Volume can mislead even when comparing how actively different stocks trade. A lower-priced stock can report far more shares traded despite the same amount of money changing hands. That is why trading valueThe total monetary value of completed trades: the sum of shares traded multiplied by their execution prices. is often the better comparison. But trading value is still a record of past trades. To estimate how much your own sell order might move the price right now, look at the bids.

Limit Orders: Choose Your Price

A limit orderAn instruction to trade at a specified price or better. A sell limit cannot execute below the stated minimum price. sets your price. When selling, it can execute only at your limit or higher. What happens if you place a sell limit order for 3,000 shares of B at KRW 9,950?

B · 3,000 shares · assuming the order book does not change

With the order book unchanged, the limit sell immediately executes 300 shares at KRW 10,000 and 700 at KRW 9,950. The remaining 2,000 shares wait as an ask at KRW 9,950. They cannot execute below that price, but they may remain unsold unless new buyers are willing to pay at least KRW 9,950. A market order, by contrast, executes against existing bids while accepting the risk of a lower price.

Four Checks Before Selling