Mood blends five readings taken from prices alone: the STI against its 200-day average, the share of its members above their own 200-day averages, members at 52-week highs minus those at 52-week lows, the STI's distance below its 52-week high, and one-month volatility (inverted). Each is ranked against its own last three years, and the five ranks are averaged. Every value uses only prices known on that day.

What the history shows. The steadiest result is at the fearful end: in most years that saw extreme fear, the STI was higher a year later. Extreme greed has not been a sell signal, but its strong average comes from a few years; year by year it was close to a coin toss. Each band rests on only 14–18 separate spells, so treat these as tendencies, not rules.

The 200-day average is the indicator with the longest research record. On the STI its value has been in risk, not return: days below the average were about 1.5 times as volatile and earned close to nothing. Switching in and out on it would have roughly halved the worst fall since 1987, but trading on it had no reliable edge for next-month returns once tested out of sample.

Limits. Breadth and highs/lows use today's 30 members, so before 2008 they leave out companies that later dropped from the index. There are no volume, options or survey data for Singapore here, so this is a price-based proxy for sentiment, not a direct measure. Not investment advice. Full methodology and tests.