Do you fill like this?

When stock market goes up every body says it will go further up. so you did not sell your stocks.But stock will come down and you fill better you had sold your stock.Because at that point you are earning good profit and now you stock came down even below your buying prise.I am sure you have felt like this many times. But you can not sell your stock at that time. There is a reason you have not sell your stock because which stock you had sold gone up and up.