Eg. For an aunty will put all money in bank n earn interest in FD rates. How about you?
This is a really great question, and it goes right to the hearts of differing attitudes about risk, and the eternal question of "how aggressive should my portfolio be?".
I have my favourite short-hand answer: "100 minus your age in stocks, and the rest in bonds" (or "110 minus your age in stocks", as it is right now because I think bonds are expensive). But that's just a rule of thumb - what you want to know is,
why is that the rule?
The reason is that as you get older, your tolerance for volatility decreases. If you were 65 in 2008, and you were 100% in stocks, then you lost half your portfolio just as you were about to retire and you got absolutely f*cked. But if you were 25 in 2008, and you were 100% in stocks, then you still lost half your money but you're able to sit back and wait for the market to come back.
The idea behind "100 minus your age" (or "110 minus your age" or even "120 minus your age", which I think is just a bit aggressive) is that it forces you to scale down your stock holdings and move into bonds as you get older, which provides two things:
1) A less volatile portfolio, because it's more bonds and less stocks;
2) A steady stream of income from those bonds without having to go through the hassle of selling stocks to fund your retirement.
So it's not a bad idea for Aunty Mabel to be 60% in bonds if she's 70 years old and retired. She needs stability rather than the possibility of huge capital gains. But 21-year-old Billy-Bob shouldn't be 60% in bonds, even if he's convinced that the world is about to implode - because even if the world DOES implode, and stocks drop 50% for the second time in two decades, Billy-Bob can afford to sit on his hands and wait for the market to come back to him.
This (or a variation of it) is the idea behind the "target-date funds" that are becoming popular over here in the USA. Basically, you pick a fund that's targeted to the date you're going to retire (for example,
Vanguard offers a "2015" fund, a "2020" fund, all the way through to "2060"); you just plunk your cash in the target-date fund, and Vanguard handles all the heavy lifting of scaling down your stock holdings and scaling up your bonds so you don't have to think about it. (
This video explains the "glide path" - as Vanguard calls it - very nicely.)