RE: DividendsSomday,
You are correct. You will continue to earn $4K per annum from the investment regardless of if the share price goes up or down. The dividend is a function of how many shares you own and that stays constant. This is assuming the share price moves based on market volatility and not because of changes to the dividend.
Now, you could invest in a dividend reinvestment plan which would take your $4K and buy more shares with that dividend. So with your $4K you would get an additional 80 shares after year 1. The following year you would receive a larger dividend since you now have 2,080 shares times $2 which gives you a dividend of $4,160.
The issue with yield is that it is purely a function of the share price. So if the stock dropped by 50% the yield would increase to 8%, but you would still receive only $4K since that is the number of shares you own. Conversely, if the stock doubles, then the dividend yield would be only 2%.
Simply put, yield is based on present market value and has zero interest in what your purchase price was.
In most cases, companies that have a 4% dividend yield, a huge spike in S/P often signals a high likelihood of an increase to the dividend as well. So if a stock doubled, there is a decent chance the dividend amount will also double.
Hope that helps.