Recently, a friend asked me, "Can I still sell when a stock hits the limit up?"

This is actually a very good question because many beginners get confused by this phenomenon.
I've organized what I've learned over the years in the stock market to share with everyone.

Let's start with the conclusion: you can definitely sell when the stock hits the limit up, and you can also sell when it hits the limit down, but the key is whether you can actually execute the trade.
These two situations are quite different, so let's discuss them slowly.

Limit up and limit down essentially mean that the stock price has reached the maximum or minimum allowed for the day.
In Taiwan's stock market, the price change limit is restricted to plus or minus 10% of the previous day's closing price; if it exceeds this range, the price is frozen.
For example, if TSMC closed at 600 yesterday, today it can only go up to 660 or down to 540 at most.
When the stock price hits this limit and cannot move further, either the buy orders or sell orders will pile up, and the price chart will turn into a straight line.

Now, back to the most important question you want to know: can you sell at the limit up?
The answer is yes, but it depends on the situation.
When a stock hits the limit up, there are far more buyers than sellers, so if you place a sell order, it will usually be executed immediately.
Conversely, if you want to buy at the limit up, you'll need to queue because many people are already waiting to buy at that price.
Sometimes your buy order might not even get in; you'll have to wait for the price to pull back before you have a chance.

When it hits the limit down, the situation is completely reversed.
At this point, many want to sell, but few want to buy.
If you place a buy order, it will be filled immediately because many are eager to get rid of their shares.
But if you place a sell order, you'll need to wait in line, and whether it gets executed depends on if someone is willing to take the stock at that price.

Here's a practical tip:
If a stock has really hit the limit down and you want to exit, never wait until the limit down to sell.
Because once it hits the limit down, there's a high chance it will continue to decline over the next few trading days.
The smartest move is to place a sell order during the pre-market auction, as the trading rules prioritize price, then time—placing your order early gives you a better position.
Once you've placed the order, don't mess with it; many people see it hasn't sold and rush to cancel and re-enter, which can push your order to the back of the line, making it harder to execute.

If a stock at the limit down suddenly shows a large buy order at the limit price, it could be that the big players are stepping in to buy.
In this case, you might consider selling quickly, but act fast because opportunities are usually very short-lived.
Additionally, many stocks at the limit down will see a liquidity spike in the last 10 or so minutes before the market close, as funds come in to buy cheap shares—this is often the last chance to sell for the day.

Why do limit up and limit down occur?
Limit ups are usually caused by good news from the company, such as strong earnings reports, large orders received, or positive policy stimuli that flood the market with capital on a certain theme.
Sometimes, technical strength or large investors locking in their positions can also trigger a limit up.
Limit downs, on the other hand, are caused by bad news like earnings misses, company scandals, or industry downturns.
Market panic, major investors offloading shares, margin calls, or technical breakdowns can all lead to limit down.

An interesting contrast is that the US stock market has no concept of limit up or limit down.
Instead, they use circuit breakers, which temporarily halt trading when prices move too violently, giving the market a cooling-off period.
For major indices, if the S&P 500 drops more than 7% or 13%, trading is paused for 15 minutes; if it drops 20%, trading is halted for the entire day.
For individual stocks, if the price moves more than 5% in a short period, trading may be temporarily suspended.

What should you do when encountering limit up or limit down?
The most important thing is to stay rational and avoid blindly chasing highs or selling lows.
First, understand why the stock is hitting the limit up or down, then decide whether to enter.
If a stock hits the limit down due to short-term market sentiment or external factors but the company's fundamentals are intact, it often rebounds, so holding or small-scale buying might be a good strategy.
Similarly, when a stock hits the limit up, don't rush to chase; first confirm whether the positive news is real and sustainable.

If a stock rises on good news and hits the limit up, you can also consider buying related upstream or downstream companies or similar stocks.
For example, when TSMC hits the limit up, other semiconductor stocks often move together.
Some Taiwanese stocks are also listed in the US, like TSMC (TSM), which can be bought on US exchanges through foreign brokers or via cross-border trading, making it more convenient.
So, can you sell at the limit up? Yes, you can.
The key is to understand timing and strategy.