Risk and Rates of Return(英文版)(ppt 55頁)

Risk and Rates of Return(英文版)內容提要：
What is investment risk?Investment risk pertains to the probability of actually earning a low or negative return.
The greater the chance of low or negative returns, the riskier the investment.
Do the returns of HT and Coll. move with or counter to the economy?
HT: Moves with the economy, and has a positive correlation. This is typical.
Coll: Is countercyclical of the economy, and has a negative correlation. This is unusual.
General statements about risk
Most stocks are positively correlated. rk,m ? 0.65.
s ? 35% for an average stock.
Combining stocks generally lowers risk.

..............................