When a trendline acts as a resistance, it means the price repeatedly faces selling pressure near that downward-sloping line, which connects lower highs in a bearish trend. Each time the stock rallies toward the trendline, sellers step in and push the price down again, confirming that the overall momentum is weak and supply is dominating demand. This dynamic resistance level keeps rejecting price until a strong breakout occurs with volume, which may signal a potential trend reversal