Why share prices move
The answer
A share price moves when the expectations of buyers and sellers change — not when news is good or bad. A company can report record profits and the stock can fall, because the price already contained a bigger number than the one that arrived.
Why this costs you money
You hold a stock. The company reports its best quarter in its history. Profit is up 30%. You feel good on the way to the app.
The stock is down 8%.
Now comes the expensive part. Most people do one of two things here. They sell in confusion, or they buy more because "the market has got it wrong". Both decisions are made without knowing what actually happened, and both are made inside the first 20 minutes, which is the worst possible time to decide anything.
The second version of this mistake is quieter and costs more over a lifetime. Your stock falls 4% and you spend the evening reading about the company, looking for the flaw. There was no flaw. The whole market fell 3.7% that day and your stock did nothing at all. You have just spent 2 hours and a night's sleep analysing a company event that never happened.
Traders lose money reacting to moves they have not identified. A move has to be identified before it can be interpreted, and almost nobody does the identification step.
How it works
A price is not a fact about a company. It is the point where the last buyer and the last seller agreed.
That agreement contains everything both of them already believe about the future — the profits they expect, how certain they feel about those profits, and what else they could do with the money instead. When any one of those 3 things changes, the agreement moves.
This gives you the sentence that explains almost every confusing price move:
The price already contains the expected news. It moves on the surprise.
If the market expects profit to grow 35% and it grows 30%, that is very good news and a negative surprise at the same time. The price falls. Nobody is being irrational. The buyers who were paying for 35% are no longer willing to pay it.
Three forces move a price, and they are worth separating because they need different responses.
| What changed | What it looks like | How long it lasts |
|---|---|---|
| The company | This stock moves, its peers do not | Can be permanent |
| The sector | Every company in the industry moves together | Weeks to years |
| The market | Nearly everything moves the same way on the same day | Usually the shortest |
Most single-day moves in an individual stock are mostly the third one. Most people interpret all of them as the first.
What it tells you, and what it does not
A price move tells you that expectations changed. It does not tell you who changed their mind or why.
It does not tell you the direction is correct. A price is the average of a crowd's opinion, and a crowd is very good at some things and very poor at others. Crowds are excellent at absorbing a known, public, numerical fact quickly. They are poor at pricing anything that requires waiting 5 years.
And a price move tells you nothing about the size of the underlying change. Small changes in expectations about the distant future produce large moves today. This is why a company whose profits are stable can have a share price that is not.
The decision rule
Before you react to a price move, answer 2 questions in this order.
1. Did the market move? If the index moved almost the same amount, your stock did not do anything. There is nothing to interpret.
2. If the stock moved on its own — was this a surprise, or was it news? News that everyone expected is already in the price. Only the gap between expectation and reality moves it.
If the answer to the first question is "yes, the whole market fell", you can close the app. That is not a lazy conclusion. That is the correct one, and reaching it in 30 seconds is a skill.
Try this now
This takes 2 minutes and it changes how you read every red day for the rest of your life.
- Open your holdings or watchlist. Find the stock with the biggest single-day move in the last month, up or down. Note the date and the percentage.
- Now open the index for that same day — NIFTY 50 if it is an Indian stock, S&P 500 if it is a US stock. Most apps let you set the chart to 1 month and hover on a date.
- Write down the index move for that same day.
- Subtract.
Your stock's move − the index move = the part that was actually about your company. - Repeat for 2 more of your holdings on that same date.
What you should see. On most days, a large part of your stock's move disappears in step 4. A 4% fall becomes a 0.6% fall once you remove the market. And when you do this for 3 holdings on the same day, you will usually find they all moved in the same direction by similar amounts — which is the proof that you were watching one event, not three.
Occasionally you will find a day where the subtraction leaves something big behind. That is a company event, and that is the day worth reading about. You have just learned to tell the difference.
Three real cases
1. HDFC Bank, 17 January 2024 (India) — record profit, sharp fall India's largest private bank reported a record quarterly profit. The stock fell around 8% in a single session, one of its worst days in years, and dragged the NIFTY down with it. The profit number was not the problem. Deposit growth and margins came in below what analysts had built into the price. A record result was still a negative surprise.
2. Meta Platforms, 3 February 2022 (United States) — one number, a quarter of the company Meta reported quarterly revenue of over $30 billion and remained hugely profitable. It also reported the first decline in daily users in its history. The stock fell roughly a quarter in one day, wiping out over $200 billion of market value — the largest single-day loss in US market history at the time. The profits were enormous. The story about growth had changed, and the price was built on the story.
3. Nvidia, 27 January 2025 (United States) — no company news at all A Chinese lab released a model that appeared to match far more expensive systems at a fraction of the training cost. Nvidia had announced nothing. Its last results were unchanged. Its customers had cancelled nothing. The stock fell around 17% in a day, close to $600 billion of value, because the market revised its belief about how many chips the world would need. Nothing happened to the company. Everything happened to the expectation.
The question that resolves it
When a stock moves on results day, a novice asks: were the numbers good?
An expert asks: what number was already in the price?
The first question can always be answered from the press release. The second one requires knowing what was expected before the release — and that is the only one of the two that explains the price.
What would make this wrong
If prices moved on news rather than on surprise, then good results would reliably be followed by rising stocks. They are not, and any 3 results seasons will show you that.
The honest limits are 2.
First, this framework assumes there is a real market of informed buyers and sellers. In a thinly traded small company, a single large order can move the price 10% with no change in anybody's expectations. There, the move genuinely is meaningless.
Second, "the market already knows" is not always true. Markets absorb public numbers quickly. They absorb slow structural changes badly. If you conclude that the price is always right, you have taken a useful idea one step too far.
In India
Results are announced quarterly, and companies must disclose material events to the exchanges under SEBI's disclosure rules. The announcements appear on the NSE and BSE websites, often before they appear anywhere else.
Three things move Indian prices that have no direct equivalent elsewhere:
- FII flows. Foreign institutional investors buy and sell large amounts, and the daily figures are published. Heavy foreign selling can pull the whole market down on a day when nothing domestic has happened.
- The Union Budget, presented on 1 February. A single speech re-prices whole sectors within hours.
- RBI policy decisions, which move banks, non-bank lenders and property companies together.
Circuit limits also matter. Individual stocks have price bands (commonly 5%, 10% or 20%) beyond which trading pauses. A stock stuck at its upper circuit has not finished moving — it has run out of permission to move. Do not read the closing price as the settled opinion.
In the United States
Companies report quarterly, and most give guidance — their own forecast for the coming quarter. Guidance moves prices more often than results do, because results are about the past and guidance is about the future.
Wall Street publishes a consensus estimate before every result: the average of analysts' forecasts. This is the number the price is built on, and it is freely available. When you read that a company "missed", it missed that number, not any objective standard.
Two more forces are specific to the US market:
- The Federal Reserve. Interest rate decisions and the language around them change what every future rupee and dollar of profit is worth today. This is why a rate meeting can move stocks that have nothing to do with borrowing.
- After-hours trading. Most US results are released after the close, so the first violent move happens when few people are trading. The opening price the next morning is often far from where the after-hours move started.
Where they differ, and what that tells you
The difference is the availability of the expectation.
In the United States, the number the price is built on is published in advance and quoted everywhere. You can read the consensus estimate, then read the result, and calculate the surprise yourself before the market opens.
In India, analyst estimates exist but are far less visible to a retail investor, and coverage thins out quickly below the largest 100 companies. For a mid-sized Indian company, there may be no published expectation at all.
What that tells you is practical. In the US, "the market already knew" is usually true and you can verify it. In India, for a company outside the top tier, it may genuinely not be true — the expectation was never formed publicly, so the news is real news when it lands.
This is the honest reason careful work on smaller Indian companies can still pay. It is also the reason those same stocks move so violently: there was no consensus to be surprised, so the whole adjustment happens at once.
Carry this
- Price moves on the surprise, not on the news.
- Subtract the index before you interpret anything.
- If you cannot say what was expected, you cannot explain the move — and you should not be trading it.
Knowledge check
Related
- What is a share?
- What is a stock exchange and how orders are matched
- What a stock index actually measures
- Circuit breakers and trading halts
- ← How the market works