What is Trend Line?

Drawing accurate trend lines is both art and science. An uptrend line requires at least two higher lows; a downtrend line requires at least two lower highs. A third touch confirms the trend line's validity. The more times a trend line has been touched and held, the more significant it is considered — and the more significant the signal when it eventually breaks.

Trend lines serve as dynamic support and resistance. In an uptrend, the trend line acts as support where buyers are expected to step in. Traders buy bounces off the trend line and set stops below it. In a downtrend, the trend line acts as resistance, with traders selling rallies toward it.

The angle of the trend line matters. Very steep trend lines (above 45 degrees) are unsustainable and tend to break quickly. Moderate trend lines (20-45 degrees) represent healthy, sustainable trends. Flat trend lines indicate a range-bound market. When a steep trend line breaks, price often consolidates before resuming the trend along a less steep line.

Trend line breaks combined with volume and other indicators generate powerful signals. A break of a major uptrend line (held for months) on heavy volume is a significant warning that the trend may be reversing. However, many trend line breaks lead to consolidation rather than reversal, so additional confirmation is valuable.