So to your question, that’s why I come up with my theory to match the portfolio weight to the counter’s expected dividend yield. It gives me a quick way to identify what might be unrealistically priced, then starts my process to think how much I want to invest or divest of the counter. My rule of thumb is if I dont have a good idea how to do the math, but I decided on the direction, then just do 1/3 - ie buy 1/3 or sell 1/3 if no better math.
As for whether to buy or sell stocks, I run my weekly screening criteria using sgx, then see if the counter remains on my screenlist. If it doesn’t, and I am quite free, I expand the criteria and read some of its updates to get more info on why its not meeting my criteria. If it repeatedly fails, and I cant justify if the market is being plain stupid, I just sell.
I do the homework then go through my thought process if its just better to let it go. The loss is the secondary part because mr market can be quite wrong quite often.
I used to do this top 18 rule. Only 18 counters, to buy one (and already have 18 counters), then I need to sell one. It was a good process kinda of like playing survivor and deciding who was the lesser evil. But I obviously let loose a bit recently and up to 23 counters. I have in my mind who the top 10 might be, but really have tough time deciding on the next few. So I guess I would be playing Survivor with them soon again.