You purchased a stock for $\$30$ one year ago. This year it's worth $\$38$ and it paid you a dividend of $\$0.50$ since you bought it. What is your dollar return?
You purchased a stock for $\$30$ one year ago. This year it's worth $\$38$ and it paid you a dividend of $\$0.50$ since you bought it. What is your percent return?
You purchased a stock for $\$30$ one year ago. This year it's worth $\$38$ and it paid you a dividend of $\$0.50$ since you bought it. What is your dividend yield?
You purchased a stock for $\$30$ one year ago. This year it's worth $\$38$ and it paid you a dividend of $\$0.50$ since you bought it. What is your capital gains yield?
The Efficient Market Hypothesis states that stock prices (or any other prices in an efficient market) completely reflect all relevant and available information. This means that the returns to investors are only compensation for the financial risk that they are bearing. There is no "free-lunch".
The intuition behind the EMH is relatively straightforward: suppose you knew that the stock of a company was going to increase in value by 10$\%$ tomorrow. You would likely buy the stock today. If you continued to buy the stock today, this would cause price pressure (think supply and demand), which would increase the price.
A stock had returns $10\%$, $15\%$, $4\%$ and $8\%$ over the past $4$ years. What was the arithmetic average return?
A stock had returns $10\%$, $15\%$, $4\%$ and $8\%$ over the past $4$ years. What was the geometric average return?
A stock had returns $10\%$, $15\%$, $4\%$ and $8\%$ over the past $4$ years. What was the standard deviation of returns? [Remember $\bar{R}=9.25\%$ from the earlier example.]
$\sigma_R = \left[ \dfrac{(0.1-0.0925)^2+(0.15-0.0925)^2+(0.04-0.0925)^2+(0.08-0.0925)^2}{4-1}\right]^{\frac{1}{2}}$