An investor has designed a risky portfolio based on two stocks, A and B. The standard deviation of return on stock A is 20% while the standard deviation on stock B is 30%. The correlation coefficient between the return on A and B is 0.25. The expected return on stock A is 25% while on stock B it is 30%. If the investor actively manages his portfolio and alters his portfolio risk by moving from an equal weighting scheme to an optimal weighting scheme, the benefit accrued to the investor in terms of risk is __________.