on Foresight, How could we have known that a company has high operating cost

[Temperament]

I think you are speaking base on hindsight. Back then even if you knew of someone in engineering you won't have come to the conclusion that they are under-maintain their trains. Instead your conclusion would be that they have purchased such reliable trains and the whole system is so well design such that there is very low maintenance required. A very superior business model with high returns on asset as until then the records said so.

The only way you could have avoided such a disaster investment is if you knew the trains is about to break down from the insiders but that would bother on insider trading. Example is the SAC Martomar case where he knew the drug is going to fail qualification. Nowadays scuttlebutt is eye with caution. if you knew too much you cannot trade on it, too little and info is of no use.

Yes, it is probably hindsight. But, there were no way to tell whether SMRT was diligently doing its maintenance from annual reports, ,analyst reports, going to AGMs, taking MRT or talking to staffs in MRT stations. The only possible source of information was likely to come from those that were doing the maintenance and the attrition rate of the engineering division. I could not verify but I guessed that the engineering division was likely to have pretty high attrition rate due to the overemphasis of the profit centre.

The only anti-dote to a rotten egg which is unavoidable is diversification with a basket of undervalue stocks.

I agree. It is difficult to know that it is a rotten egg from appearance until someone cracks it or tells you the production date.

i thought Ms. Saw cracked the egg quite prominently, publicly. At this time, if you had bought before she came in, you still could sell with some profit.