This is a very interesting question and thanks @OmkarT for sharing your inputs.
My take is that, you can make error back in 2014 and invest in Sun Pharma and Lupin. We as retail investors have limited tools and capability which are available to have a clear view of future.
But good part about about investing is that the returns are positively skewed.
“Max you can lose is 100% but there is no limit for gains in investing,” says Prof Sanjay Bakshi [1]
If you have a portfolio of 15-20 stocks which are spread across different sectors and out of this 25-30% of your portfolio is of bad stocks and remaining portfolio of good stocks. Then, the remaining portfolio of good stocks not only makes up for that losses but also gives superior returns.
You can finalise the approach to shortlist stocks in your portfolio. Check the stocks which make the cut in 2014. And see the percentage of bad stocks selection from it. If it is on lower side (25-30%) then you can ignore them and enjoy the power of compounding from the remaining good stocks in your portfolio.
[1] Source: “Max you can lose is 100% but there is no limit for gains in investing,” says Prof Sanjay Bakshi