What it means
The idea comes from technical analysis, which studies past price charts to look for patterns. If a share has dropped to $50 three times and bounced each time, traders will mark $50 as support.
If it has risen to $60 several times and then fallen back, $60 becomes resistance. The logic is about behaviour.
Buyers who missed an earlier bounce may buy again at the same level, and sellers who regretted not selling at an earlier high may sell as the price returns. The more times a level is tested, and the more trading volume there is at that level, the more traders tend to respect it.
Levels are not permanent walls. When a price breaks decisively through resistance, that old ceiling often becomes the new floor, and when it breaks below support, the old floor often becomes the new ceiling.
Traders call a clean move through a level a breakout. Practical use is mostly about planning trades and managing risk.
A trader might buy near support, place a stop-loss order (an instruction to sell automatically if the price falls to a set level) just below it, and aim to sell near resistance. This lets the trader compare the possible loss with the possible gain before committing money.
For a business audience the concept appears when treasury teams time currency purchases, when investor relations teams read how the share price reacts to news, or when employees decide when to sell vested shares. It is a tool for timing and not a measure of value.
It is important to stay realistic about its limits. Support and resistance describe what has happened, and many academic studies question how reliably it predicts what happens next.
Treat the levels as reference points, never as guarantees.
In practice
Real-world examples
Example 1
An analyst charts a share that has bounced off $120 on four occasions over a year. She marks $120 as support and tells her clients to watch closely for a drop below it, which might signal a deeper fall. She also notes the trading volume at each bounce, because heavier volume makes the level more meaningful.
Example 2
A company's finance team plans to convert foreign earnings into dollars. The treasury manager notices the exchange rate has repeatedly stalled at the same level and decides to convert half the amount now and the rest if the rate breaks through. This splits the risk of picking the wrong moment and keeps the budget on track.
Example 3
An employee holding vested shares sees the price approach a ceiling it has failed to cross three times. She decides to sell part of her holding near that level to lock in a gain and reduce her exposure to her employer's stock.
Think of it
Think of a ball bouncing inside a squash court. The floor is support, stopping the ball from falling lower, and the ceiling is resistance, stopping it from flying higher. The ball bounces between them until someone hits it hard enough to break through the roof.
Formula
Calculation
Reward-to-risk ratio = (Resistance level - Entry price) / (Entry price - Stop-loss price)
A trader buys a share at $50, which is near support. The stop-loss is set at $48, just under support, and the target is $56, just under resistance. The possible gain per share is 56 - 50 = $6 and the possible loss is 50 - 48 = $2. Reward-to-risk ratio = 6 / 2 = 3, so the trade aims to win $3 for every $1 it risks.Case study
Seen in the real world
Redwood Treasury Partners is an illustrative, fictional advisory firm that helps small exporters decide when to convert foreign income. One client regularly received payments in another currency and worried about timing.
The adviser charted two years of rates and found a clear ceiling that the currency had touched five times without breaking. She suggested converting a third of expected receipts each time the rate came within 1% of that ceiling.
Over the following year, two of the three conversions happened near the ceiling and the third after a breakout. In this illustrative story, the client's average rate improved modestly, but the adviser stressed that the levels were guides and not guarantees. She also reminded the client that a different set of events, such as a central bank announcement, could push the rate through any level without warning, which is why the plan always kept some amount unconverted.
Watch out
Common mistakes
- Treating support and resistance as exact prices, when they are better thought of as zones.
- Assuming a level that held in the past must hold again, when each test can weaken it.
- Trading on the levels alone and ignoring the company's results, news and the wider market.
Questions
People also ask
What is a breakout?
It is a move of the price clearly beyond a support or resistance level, usually on higher-than-normal trading volume.
Why does old resistance often become support?
Traders who bought at the breakout level tend to defend it, and others who missed the move buy when the price returns to it.
Does support and resistance work for every asset?
It is used on shares, currencies, commodities and more, but it works best in markets with plenty of trading activity.