Explain why the slope of the efficient frontier decreases at higher levels of risk (standard deviation). Why does this fact matter to investors seeking to achieve higher than market (e.g. S&P 500) returns? In other words, what do active managers need to do in terms of portfolio construction and asset selection to outperform the S&P 500 in this case? Please explain how the changing slope translates to the risk/return trade-off for investors.