PEG Ratio Backtest

The Price-to-Earning to Growth ratio, commonly referred to as the PEG ratio, is a simplistic valuation rule of thumb. A value less than one potentially indicates an undervalued stock and a ratio greater than 1 might indicate overvalued stock. This simplistic and somewhat controversial ratio was popular in the ’90s but has more recently grown out of favor . The PEG ratio is calculated as follows:

PEG = PE ratio / Earning per share growth estimate

There are many versions of the PEG ratio based on different methods used to estimate earnings per share (EPS) growth rates. The PEG ratio version used for this backtest uses  past 12 months earnings and and next year’s EPS consensus estimate whenever possible.

Let’s take a look at a backtest of this ratio to see how it works. I used the data and backtesting tool provided by Portfolio123. The Portfolio123 backtesting eliminates the problem of survivorship bias by using point-in-time and retaining data on stocks that have gone to zero. This backtest uses the same filtered universe of stocks as my recent Current Ratio Backtest. I’ve designed the filtering criteria for this backtest specifically for individual investors and with a focus on enhancing data quality. The filters include the following criteria:

  1. No OTC stocks. Stocks not traded on the New York Stock Exchange, NASDAQ, or American Stock Exchange markets are excluded. The quality of fundamental stock data for OTC can be somewhat lower and less timely that that for stocks traded on major exchanges.
  2. No ADRs. Fundamental data for foreign American Depositary Receipt can include errors due to currency exchange, different accounting standards, and share count.
  3. Liquidity test. The average daily total amount traded over the past 60 trading days must be larger than $100,000.  This amount was selected so that a $1 million dollar portfolio could hold 100 positions and that each new $10,000 position would not exceed 10 percent of a day’s trading volume. The liquidity test also ensures that the backtest has reliable market price information for any of the stocks that are being tested.
  4. Market Cap > $50 million. Nano cap stocks are excluded to help improve data quality. This filter also ensures that positions in a modest sized portfolio never exceed one percent of shares outstanding or the available float for a company.
  5. Price > $1. True penny stocks are excluded due to various information issues and manipulation of these stocks.
  6. PEG ratio > 0. This filter insures we are looking at stocks that actually have valid data on the PEG ratio.

After these filters are applied, we are left with approximately 1,800 to 2,700 stocks. These stocks are then ranked by the criteria being tested; in this case, we are testing the PEG ratio. The lowest 20 percent of stocks ranked by the PEG ratio are placed in the first quintile and the next 20 percent in the second quintile and so forth until we have five portfolios of stocks. The portfolios are rebalanced every 12-months and compounded annually to more realistically replicate what an individual investor might be expected to do to avoid higher short-term capital gains tax and trading costs. The following 5 charts display the quintile returns for the PEG in red and the S&P 500 Equal Weight Index in blue.  The first quintile includes the companies that had the lowest PEG ratios and the 5th quintile includes the companies that had the highest PEG ratios.

PEG Ratio Quintile Returns – 2000 – 2013

PEG Ratio Backtest 1st Quintile
PEG Ratio Backtest 1st Quintile


PEG Ratio Backtest 2nd Quintile
PEG Ratio Backtest 2nd Quintile


PEG Ratio Backtest3rd Quintile
PEG Ratio Backtest 3rd Quintile


PEG Ratio Backtest 4th Quintile
PEG Ratio Backtest 4th Quintile


PEG Ratio Backtest 5th Quintile
PEG Ratio Backtest 5th Quintile


PEG Ratio Backtest Universe
PEG Ratio Backtest Universe


Summary of Results for the PEG Backtest

Backtest Results for the PEG Ratio
14-year Backtest Results for the PEG Ratio
Bar chart of the average annual excess returns for the PEG ratio
Average annual excess returns from 2000 to 2014 for the PEG ratio

This backtest of the PEG ratio reveals that the first quintile outperforms the S&P 500 Equal Weight Index benchmark. The second through fifth quintiles have lower average annual excess returns than each of the previous quintiles and the overall trend in excess returns is a linear decrease as the PEG ratio increases.  These results are as you would expect.  The main issue to note with this fundamental ratio is that the change in excess returns from the 1st to the 5th quintile is not as dramatic as the PE ratioreturn on enterprise value or the enterprise value to EBITDA backtests.

What are your thoughts on the PEG ratio?


7 thoughts on “PEG Ratio Backtest

  • December 12, 2014 at 6:38 pm

    I am the originator of the PEG Ratio. Please contact me if you have questions about its origin.

  • December 12, 2014 at 6:42 pm

    I am the originator of the PEG Ratio. Are you interested in its origin and history. I can provide this since I originated this is 1969. Do you want to know more? Please contact me at the above email address. Thanks.

    Mario V. Farina

  • September 4, 2015 at 4:01 pm

    Please contact me if you’d like a free book
    A Beginner’s guide to successful investing in the Stock Market by Mario V. Farina

  • March 9, 2018 at 10:17 am

    Hi George,
    how solid is this backtest? Ive read about quite a few backtests of PEG that was quite bad. What is your take on this? Im really interested in your answer :)

    Best regards


  • May 21, 2021 at 11:29 am

    Peg Ratio . Excellent Info / Research.
    Exactly what I was looking for .

    Thank You

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