20-20 rule in stock selection

ET has this interesting article on stock selection in a bearish/bullish market. The idea it churns out is something like this.

When the markets are declining, people don’t buy stocks because they doubt that the stock prices would decline further, resulting in a loss or else they will wait to buy the stock at the lowest point. But the article argues that waiting to buy stocks at the lowest point may not be fruitful because, less and less people sell stocks as its price nears the lowest point.

On the other hand, when the markets are bullish, people don’t sell stocks because they doubt the stock prices would go higher or they wait for the stock prices to reach the highest point. And, here the article argues that at the highest point there would be less and less people willing to buy the stock and hence selling it at the highest price may not be possible.

Due to this phenomenon, the article suggests that in a bear market, buy stocks when the market goes down by 20%, rather than waiting for it to touch the lowest point and in a bull market, sell stocks when the markets goes up by 20% rather than waiting for it to touch the peak.