I read from various sources (eg. Exotic Options and Hybrids, M. Bouzoubaa) that the correlation sensitivity of Rainbow options (say a call price on a basket made of 50% of the best stock, 20% of the worst, 30% of the 3rd one) is uncertain due to 2 opposite effects: 

- Increasing correlation would increase the overall basket volatility, thus tends to push the option price higher

- Increasing correlation would decrease the Forward price, thus tends to push the option price lower

I do not understand the reason for the 2nd point - how come an increase in correlation decreases the Forward price?