Trendline
A diagonal line connecting successive swing highs or lows that maps the slope and direction of a market trend.
Definition
A trendline is a straight line drawn on a price chart that connects a series of ascending lows in an uptrend or descending highs in a downtrend. Unlike horizontal support and resistance levels, trendlines are diagonal — they rise or fall with price over time and act as dynamic barriers. A valid trendline requires at least two anchor points; a third touch without a breach is considered confirmation of the line's relevance.
Why it matters
Trendlines help traders distinguish between retracements within an ongoing trend and genuine reversals. In Indian markets, positional and swing traders on NSE and BSE use trendlines to time entries on pullbacks: buying near an uptrend line during a correction and selling near a downtrend line during a bounce. F&O traders use trendline breaks as triggers to initiate or exit option positions, often combining the signal with volume confirmation and open interest shifts. A steeply angled trendline tends to break sooner; shallower, well-tested lines carry more weight.
How it works
To draw an uptrend line, identify two or more successive higher lows on the chart and connect them with a straight line extended to the right. The line acts as dynamic support — each time price pulls back to the line, buyers are expected to defend it. For a downtrend, connect successive lower highs; the line acts as dynamic resistance. A decisive close beyond the trendline — ideally on above-average volume — signals that the trend may be reversing or pausing significantly. Traders also watch for price to break a trendline, retest it from the other side, and then continue in the breakout direction.
Example
Suppose NIFTY 50 makes lows at roughly 21,800 and then 22,100 over eight weeks — a series of higher lows. Connecting these two points gives an uptrend line. On a hypothetical third pullback to approximately 22,350, traders buy NIFTY futures or call options, placing a stop below the trendline. If NIFTY subsequently closes below the trendline on heavy volume, the trade is exited as the uptrend may be breaking down. These figures are illustrative and do not represent any actual market levels.
Combine trendlines with live OI data
See how open interest shifts when price approaches key trendlines on TradePulse's live charts.