What is Support and Resistance? Definition, Formula, and Example
Support and resistance are price levels where a stock has repeatedly stopped falling or stopped rising, marking zones where order flow — not any formula — has historically shifted the balance between buyers and sellers.
What is support and resistance?
Support is a price level where buying pressure has repeatedly overwhelmed selling pressure, stopping a decline and turning price back up. Resistance is the mirror image: a level where selling has repeatedly overwhelmed buying, capping an advance and turning price back down. Neither is a formula-derived output — both are descriptive labels traders apply after seeing price react at the same area more than once. The underlying mechanism is real, even if the label is subjective: large resting orders, breakeven points for traders who bought or shorted at that level, and round-number psychological anchors all cluster order flow at specific prices, and that clustering is what makes the level "hold" until it doesn't.
How support and resistance levels are identified
There's no single formula, but chartists converge on a handful of criteria: prior swing highs and lows (a level price has visibly reversed from before), round numbers ($50, $100, $300 — order flow clusters here because humans set orders at clean numbers), moving averages (the 50-day and 200-day are common dynamic support/resistance lines), and volume-at-price data (price levels where the most historical volume traded tend to act as support/resistance because the most traders have a position anchored there). A level is generally considered more significant the more times price has touched and reversed from it, and the more volume traded when it did.
Worked example
AAPL set an all-time closing high of $315.20 on June 2, 2026, inside a 52-week range of $201.50 to $317.40. The $313–$317 zone functioned as resistance through June: price pushed into it, failed to hold, and pulled back. By July 2, 2026, AAPL closed at $308.63, up 4.84% on the day — a sharp bounce that stopped in the $300–$305 area, which had acted as support on the pullback from the highs. The $201.50 level, the 52-week low, is the more extreme support case: it's the price at which sellers were fully exhausted over the past year, making it a reference floor even though it's far from the current price. None of these levels were calculated — they were read directly off where price visibly reversed.
When traders use it
Traders use support and resistance to place entries (buying near support, shorting near resistance), size stops (a long position below support has a defined invalidation point — if the level breaks, the thesis is wrong), and frame risk/reward (buying near support with resistance overhead gives a measurable target versus a measurable stop). Breakout traders do the opposite: they wait for price to close through resistance on volume, on the theory that a broken resistance level often becomes new support (and vice versa for broken support becoming resistance) — a concept closely tied to a break of structure.
Limitations and misconceptions
Support and resistance are not exact prices — they're zones, and two chartists looking at the same chart will draw slightly different lines. The concept is partly self-fulfilling (a level "holds" partly because enough traders believe it will and place orders accordingly), which means it can stop working abruptly once enough participants stop respecting it, especially around news or earnings gaps that ignore prior levels entirely. A level holding twice is not a guarantee it holds a third time — in fact, each retest without a strong reaction can weaken a level rather than confirm it, a dynamic option traders track via concepts like a liquidity sweep. The tool works better on liquid, widely-followed names and higher timeframes; on thin, low-volume stocks, "levels" are often just noise.