That support is usually a previous reaction low. The best place to sell a market is near resistance levels. Resistance is usually a previous peak. After a resistance peak has been broken, it will usually provide support on subsequent pullbacks. Know How Far to Backtrack Measure percentage retracements.
Market corrections up or down usually retrace a significant portion of the previous trend.
You can measure the corrections in an existing trend in simple percentages. A fifty percent retracement of a prior trend is most common. A minimum retracement is usually one-third of the prior trend. The maximum retracement is usually two-thirds. Draw the Line Draw trend lines .