The measure is built entirely from market prices. Share prices are not reported in SEC filings, which describe a company's financial position and results rather than what its stock trades for, so capital yield comes from exchange price data rather than from a 10-K or 10-Q. The periods most often used are a fiscal year, a calendar year, or the trailing twelve months.
Capital yield and dividend yield together make up total return. If a share bought at $50 ends the year at $54 after paying $2 in dividends, the capital yield is 8%, the dividend yield on the starting price is 4%, and the total return is 12%. Comparing the two parts shows how a company rewards shareholders: mature dividend payers tend to deliver more of their return as income, while companies that reinvest their earnings rely more heavily on price appreciation.
Prices must be adjusted for stock splits and similar corporate actions, or the measure will show a large false loss in the period a split occurs. Capital yield also reflects only the chosen start and end dates, so it can look very different if either date moves by a few weeks in a volatile market. Because it is a backward-looking market figure, it says nothing on its own about whether the business itself improved.