A share closed at ₹500 yesterday. This morning it opens at ₹515. Should you buy before it rises further, or wait to see whether it falls back?

The share has opened a gap up because its opening price is higher than its previous close. If it had opened below ₹500, that would be a gap down. Gap up and gap down trading strategies help traders assess what the price does after that opening move. The gap itself does not tell them what will happen next.

Quick Answer

A gap up means a share opens above its previous closing price. A gap down means it opens below it. Traders may look for the opening move to continue or for the price to turn back towards the previous close. Before placing a trade, check why the share moved, watch its early price range, and decide where you would exit if the trade goes against you.

What are gap up and gap down openings?
How do gap trading strategies work?
A gap up trade example
A gap down trade example
Gap and go compared with gap fill
Advantages and risks
Tips for beginners
Common mistakes
Who should consider gap trading?
Conclusion
Frequently asked questions

What Are Gap Up and Gap Down Openings?

A share opens gap up when today’s opening price is above the previous trading day’s closing price. It opens a gap down when today’s opening price is below that close.

Say a share closed at ₹500. An opening at ₹515 is ₹15 higher. An opening at ₹485 is ₹15 lower.

To compare the size of gaps in shares with different prices, use a percentage:

Opening gap percentage = Today’s open − Previous close / Previous close X 100

For the ₹515 opening, the calculation is 15 ÷ 500×100 = 3%. It is a 3% gap up. An opening at ₹485 is a 3% gap down. These are calculations based on hypothetical prices, not returns from an actual share.

Company announcements, results, or wider market news can change the price at which people are willing to trade when the market opens. A higher open shows where trading began. It does not mean the share will rise for the rest of the day.

There is one chart detail worth knowing. A share can open above yesterday’s close while still opening below yesterday’s highest price. In that case, it has opened higher than the close, but there is no complete gap between the opening price and yesterday’s trading range. You do not need to classify every type of chart gap before learning to assess an opening move.

How Do Gap Trading Strategies Work?

After a gap, traders usually watch for one of two possibilities: the price keeps moving in the opening direction, or it turns back. Here is a way to assess the situation without rushing into an order.

Measure the gap. Note the previous close and today’s open. Calculate the percentage so you know how large the opening move is relative to the share price.
Check what happened overnight. Look for a company announcement or relevant market news. If you cannot tell why the share has moved, take extra care rather than guessing.
Watch the early range. One approach is to note the highest and lowest prices reached in the first 15 minutes of regular trading. Traders call this the opening range. Fifteen minutes is an example, not a rule that works for every share or every day.
Choose the setup you are watching. A move beyond the early range in the gap’s direction may interest a trader looking for continuation. A move back through the range may suggest the opening move is weakening.
Plan the exit before the entry. Choose where you would enter, where you would leave if wrong, and how much money you are prepared to risk. Only then calculate the number of shares.
Skip the trade if conditions change. If the price races beyond your intended entry, your original risk calculation may no longer apply.

How Might a Gap Up Trade Work?

Consider a hypothetical share called ABC Ltd. It closed at ₹500 and opens the next day at ₹515. During the first 15 minutes, it trades between ₹512 and ₹518.

A trader who expects the rise to continue decides to buy only if the price reaches ₹519, above the early high. The trader’s planned exit if wrong is ₹511, below the early low.

Detail	Hypothetical price
Previous close	₹500
Today’s open	₹515
First 15-minute low	₹512
First 15-minute high	₹518
Possible buy price	₹519
Planned exit if wrong	₹511
Planned risk per share	₹8

Suppose the trader plans for a loss of ₹800. At ₹8 per share, that works out to 100 shares: ₹800÷₹8=100.

If the trader later sells at an illustrative ₹535, the gross gain is ₹535−₹519=₹16₹535 – ₹519 = ₹16₹535−₹519=₹16 per share, or ₹1,600 for 100 shares. If the exit happens at ₹511, the gross loss is ₹519− ₹511 = ₹8 per share, or ₹800.

Those figures leave out charges. More importantly, ₹800 is a planned loss, not a ceiling: a fast move could lead to an exit below ₹511. A stop order may not execute at the price used in the calculation. ₹535 is simply a number chosen to show the arithmetic, not a price the gap predicts.

If ABC never reaches ₹519, this particular entry does not occur. A gap up does not oblige the trader to buy.

How Might a Gap Down Trade Work?

Now consider another hypothetical share, XYZ Ltd. It closed at ₹800 and opens at ₹784. The opening difference is ₹16÷ ₹800 × 100 = 2%, so this is a 2% gap down.

During the first 15 minutes, XYZ trades between ₹778 and ₹787. A trader looking for a further fall considers a short sale only if the price drops to ₹777. Short selling means selling first and buying back later. The trader gains if the buyback price is lower, but loses if it is higher.

Suppose the trader sells at ₹777 and plans to exit if the price rises to ₹788. The planned risk is ₹788− ₹777 = ₹11 per share. For a planned loss of ₹550, the calculated position is 50 shares: ₹550÷ ₹11 = 50.

Buying back at an illustrative ₹765 would produce a gross gain of ₹777 − ₹765 = ₹12 per share, or ₹600 for 50 shares. Buying back at ₹788 would mean a gross loss of ₹550, assuming the order executes there. Charges and a different execution price would change the result.

Short selling needs an understanding of order types and broker requirements. A beginner can study a gap down without placing a short trade.

Gap and Go Compared With Gap Fill

A gap and go trader looks for the opening move to continue. A gap fill trader looks for the price to move back towards the previous close. Neither outcome is assured.

Question	Gap and go	Gap fill
After a gap up, what is the trader watching for?	A further rise	A move back down
After a gap down, what is the trader watching for?	A further fall	A recovery
What could go wrong?	The early move reverses	The original move continues
Which prices help assess the idea?	The early high or low	The previous close and early range

For example, ABC closed at ₹500 and opened at ₹515. Someone watching for a gap fill would look for signs that the early rise is failing and the share is moving back towards ₹500. That previous close is a useful reference price, not a guaranteed destination.

What Are the Advantages and Risks?

The main practical advantage is that a gap gives traders prices they can identify before making a decision: the previous close, today’s open and the early high and low. These can help a trader write down a possible entry and exit rather than respond to every small price change.

The risks are easy to underestimate:

The share can change direction quickly. A gap up can be followed by a fall; a gap down can be followed by a recovery.
An early breakout can fail. The price may cross the opening range briefly, then move straight back.
Your exit may not occur at the planned price. SEBI’s risk disclosure notes that rapid market moves can prevent a stop-loss order from limiting a loss to the intended amount.
A thinly traded share may be difficult to exit. If few people are willing to trade near your chosen price, the actual execution price can differ from your plan.
The opening move can create pressure to act. Entering late or taking more shares than planned can turn a manageable mistake into a larger loss.

What Should Beginners Do First?

Watch a few gap openings without trading. Write down the previous close, the opening price, the early high and low, and what happened later. This gives you practice recognising when the opening move continued, reversed or went nowhere.

Before considering a trade, decide your entry, your planned exit if wrong, and the amount you could lose. Work out the share quantity from those figures. Check whether the price is near an area where it has often turned before.

Include charges in your assessment. If the share has already moved too far or you cannot explain your exit, leave the trade alone.

What Common Mistakes Should You Avoid?

Buying only because a share opened higher. Wait to see whether the setup you planned actually appears.
Expecting every gap to fill. The price may keep moving away from the previous close.
Chasing a move after missing your entry. A later entry changes the distance to your planned exit and therefore changes your risk.
Choosing the quantity first. Decide the acceptable loss and risk per share before calculating how many shares to trade.
Moving the planned exit to avoid a loss. That changes the risk you accepted when you entered.
Keeping a failed intraday trade as an investment. Holding overnight is a separate decision, not a way to repair the original trade.

Who Should Consider Gap Trading?

Gap trading is mainly relevant to active traders who can watch the market after it opens and follow a written plan. It may not suit someone who cannot monitor a position or finds fast price changes difficult to manage.

A long-term investor may care more about why a share opened differently than about its first 15 minutes of trading. Company information and an opening price pattern answer different questions.

Conclusion

A gap up or gap down tells you where a share opened compared with its previous close. It does not tell you where the price will finish. Some traders watch for the opening move to continue; others watch for it to fail. Both approaches can lose money. If you are new to trading, start by observing what happens after the open. When you do plan a trade, set the entry, exit, and share quantity around a loss you can manage. An unclear setup does not need a trade.