QUOTE(MUM @ Dec 8 2015, 11:26 AM)

Thanks for the links....
read this Disclaimer about Diversification in the link...and is still wondering how does "Going for diversified portfolio can
Earn maximum returns with minimized risk".
Maximum return with minimum risk, i.e., The Holy Grail of Investing. Trying to steal a free lunch from capital market.
Here is how. I'll use real life example.
Take two fund;
i) RHB cash management fund at 3.7% p.a. with a standard deviation aka as volatility aka risk is 1% (Anything less than 1% can consider almost risk free liao for retail investors)
ii) CIMB - Global Titan Fund aka Titan at 21.00% p.a. with stan-dev of 8.29%
NB: I got these figures from their respective Fund Fact Sheet hence I am not using make belief values.
The rate of return is % of Titan + % in RHB-CMF = 100% or 1.00, or W(titan) + W(cmf) = 1.00
The combined volatility of both Titan + CMF is not linear but given by the formula:
= Std-dev(portfolio, p) = [(W(titan)^2 x W(cmf)^2) + (2 x W(titan) x W(cmf) x Std-dev of titan x Std-dev of cmf x corr-coeff btw Titan-cmf)] ^ 0.5
Now look at the formula again: we know that the std-dev of cmf is very small (negligible) and cmf correlation coefficient to Titan is zero.
The formula then simplified to Std-Dev, p = [W(titan) x std-dev of titan]
the risk to reward ratio of of Titan alone = 21 / 8.29 = 2.53
If you take a portfolio of half titan + half cmf; the return is 0.5 x ( 3.7 + 21 ) = 12.35% p.a
The std-dev is 0.5 x 8.29 = 4.145
Hence the portfolio risk to reward ratio now becomes = 12.35 / 4.145 = 2.98
This means that by sacrificing the return, our portfolio become more stable i.e, from 2.53 to 2.98.
This is a very simplified way of explaining modern portfolio theory. If real life, you will have more than two funds and their corr-coeff is not zero, you will need to use algorithm programming to do it.
Xuzen
Take home point: That is why when choosing a good portfolio, we want funds that have low std-dev or and their corr-coeff must be low.