Standarded deviation of returns is known in finance as volatility of returns.

A money manager can achieve any return they wanted if they took enough leverage.

Four types of money managers:

• Index fund managers: how closely their fund experience matches that of
  their index and how low they keep their expense ratio.
• Mutual fund managers: excess return(portofolio return-benchmark return); tracking error(standard deviation of excess return); information ration(excess return/tracking error);
• Venture capital&private equity;
• Hedge fund managers.

S&P 500(GSPC) aggregates the stock performance of the 500 largest companies in the US ranked by their capitalization.

Why would investors in hedge funds like to have performance that have low correlation to the major equity markets?
Hedge fund investors also invest large amounts of capital in major equity markets, and target the highest possible risk-adjusted return on their combined portfolio.