
The most well known example of this approach is the Shiller P/E ratio, also known as the CAP/E ratio (cyclically adjusted price earnings ratio). The Shiller P/E RatioĪ third approach is to use average earnings over a period of time. Using this method, Morningstar calculates Apple’s PE at about 28 (as of early August 2020). Morningstar uses this method, which it calls Consensus Forward PE. While the forward P/E ratio, as it’s called, doesn’t benefit from reported data, it has the benefit of using the best available information of how the market expects a company to perform over the coming year. The price-to-earnings ratio can also be calculated using an estimate of a company’s future earnings. For example, each of these sites recently reported the P/E ratio of Apple at about 33 (as of early August 2020). Popular investment apps M1 Finance and Robinhood use TTM earnings as well. Many financial websites, such as Google Finance and Yahoo! Finance, use the trailing P/E ratio. Factoring in past earnings has the benefit of using actual, reported data, and this approach is widely used in the evaluation of companies.

This is referred to as the trailing P/E ratio, or trailing twelve month earnings (TTM). One way to calculate the P/E ratio is to use a company’s earnings over the past 12 months. When it comes to the earnings part of the calculation, however, there are three varying approaches to the P/E ratio, each of which tell you different things about a stock. The price-to-earnings ratio is most commonly calculated using the current price of a stock, although one can use an average price over a set period of time. While the math behind the P/E ratio is straightforward-price divided by earnings-there are several ways to factor the price or earnings used for the calculation. The P/E ratio also changes as companies report earnings, typically on a quarterly basis. Since prices fluctuate constantly, the P/E ratio of stocks and stock indexes never stand still. For example, the P/E ratio of the S&P 500 currently stands at 28.61. In addition to stocks, the P/E ratio is calculated for entire stock indexes. To put it another way, given the company’s current earnings, it would take 25 years of accumulated earnings to equal the cost of the investment.

If a company’s stock is trading at $100 per share, for example, and the company generates $4 per share in annual earnings, the P/E ratio of the company’s stock would be 25 (100 / 4). Think of it this way: The market price of a stock tells you how much people are willing to pay to own the shares, but the P/E ratio tells you whether the price accurately reflects the company’s earnings potential, or it’s value over time. The P/E ratio is derived by dividing the price of a stock by the stock’s earnings.
