"No price is too high for a bull or too low for a bear" - an old Wall Street proverb It is a known fact that investors can be over-optimistic or over-pessimistic at times. When a series of good news happens, investors switch into the optimistic mode, often over-optimistic, and significantly bid up the price of a stock ditching any rational pricing theory whatsoever. Any high price will be justified by reasons like "profit will continue to grow" or even worse, "the price will simply continue to rise". Conversely, when a series of bad news happens, investors will go into the pessimistic mode and nothing can make us feel it is worth buying. I am also guilty of this. This is why I added a new feature to SGXcafe to (hopefully) help me stay rational during times like these. The question is: how do we identify over-optimism or over-pessimism? Typically, ......