Mechanical rules for investing

In the midst of the general meltdown of Zee Entertainment, I noticed an interesting tweet by the fund manager Samir Arora. Arora, who now runs his own fund company, Helios, was the fund manager for Alliance Mutual Fund in the 1998-2000 bull run. In the tweet, Arora pasted a screenshot of the Zee Entertainment stock price chart from 25 years ago - January 1998 to about April 2000. During this period, the Zee stock went up from Rs 4.58 to a peak of about Rs 778 (adjusted for a split) on February 24, 2000, and then collapsed. The tweet said, "Those were the days - by chance, it was the top holding in Alliance Funds through this bull run." Someone who replied to that tweet asked when and why did Alliance sell that fund. Arora's response was that they had to sell every day for two years because the stock was at 10 per cent of their holding, and that was the l