Support and Resistance
How traders identify price levels where buying or selling pressure tends to emerge.
⏱️ ~6 min read
Key Takeaways
- Support is a price level where buying pressure has historically tended to emerge, slowing or reversing a decline
- Resistance is a price level where selling pressure has historically tended to emerge, slowing or reversing a rise
- These levels are often identified from prior price highs/lows, round numbers, or where significant trading volume occurred
- When a support or resistance level is broken, it can sometimes act as the opposite type of level afterward ('role reversal')
The basic concept
Support refers to a price level where a stock has historically had difficulty falling below — the idea being that enough buyers have stepped in at that level in the past to absorb selling pressure and stop (or reverse) a decline. Resistance is the mirror concept: a price level where a stock has had difficulty rising above, as selling pressure has tended to emerge.
These levels are identified by looking at a price chart and noting where the price has previously reversed direction multiple times — the more often a level has been 'tested' and held, the more significance some traders attribute to it.
Why these levels might exist
Several explanations are commonly given for why support and resistance levels can form: investors who bought near a prior low may be inclined to buy again if the price returns to that level (anchoring), investors who missed selling near a prior high may sell if given 'another chance' at that price, and round numbers (like $50 or $100) sometimes attract orders simply because they're psychologically significant reference points.
It's worth emphasizing that these are behavioral explanations for an observed pattern — not laws of physics. Support and resistance levels can and do fail (get 'broken') regularly.
Example: Identifying a support level
A stock has declined to around $40 three separate times over the past year, each time rebounding to higher prices afterward.
Some traders would identify $40 as a support level — a price where buying interest has repeatedly emerged.
If the stock approaches $40 again, traders watching this level might expect another potential bounce — though there's no guarantee the pattern will repeat a fourth time.
Role reversal: when broken levels switch roles
When a support level is decisively broken (the price falls below it and stays there), some traders observe that the former support level can subsequently act as resistance — the idea being that investors who bought near that level (and are now at a loss) may be inclined to sell if the price rebounds back to their purchase price, creating selling pressure at what was previously a support level. The same concept applies in reverse for broken resistance levels becoming support.
Trendlines as dynamic support/resistance
Support and resistance don't have to be horizontal — trendlines drawn connecting a series of rising lows (in an uptrend) or falling highs (in a downtrend) are sometimes treated as 'dynamic' support or resistance, since the relevant price level changes over time as the trendline is extended.
Using support and resistance in practice
Traders sometimes use support and resistance levels to inform decisions like where to place orders (e.g., considering a purchase near support, or placing a stop-loss below a support level on the idea that a break below it might indicate the level has failed), or to gauge the significance of a price move (a stock breaking through a long-standing resistance level on high volume might be interpreted differently than a brief, low-volume poke above it).
As with other technical concepts, support and resistance are most often used as one part of a broader analysis rather than in isolation, since identifying these levels involves a degree of subjectivity — different traders may draw them at slightly different points on the same chart.
Frequently Asked Questions
How precise are support and resistance levels?+
They're often better thought of as zones rather than exact prices — different traders may identify a support 'level' anywhere within a range of a percent or two, especially on longer time frames.
What happens when a support level breaks?+
A 'breakdown' below support is sometimes interpreted as a bearish signal, and some traders watch for the broken support to potentially act as resistance afterward (role reversal) — though breakdowns can also be followed by quick reversals ('false breakdowns'), which is part of why these levels aren't treated as guarantees.
Do support and resistance levels work on all time frames?+
The same concepts are applied across time frames from minute charts to monthly charts, though levels identified on longer time frames are sometimes considered more significant by traders, simply because they reflect a longer history of price behavior.