Batting Average

What Is Batting Average?

An investment manager's "batting average" is a statistical technique used to measure a manager's ability to meet or beat an index. A batting average is calculated by dividing the number of days (or months, quarters, etc.) in which the manager beats or matches the index by the total number of days (or months, quarters, etc.) in the period of question and multiplying that factor by 100.

The higher the batting average, the better. The highest number possible average would be 100%, meaning the manager outperformed the benchmark every single period. In contrast, a batting average of 0% means the manager never once outperformed their benchmark.

Understanding the Batting Average

An investment manager who outperforms the market in 15 out of a possible 30 days would have a statistical batting average of 50%. The longer the period taken in the sample size, the more statistically significant the measure becomes. Many analysts use this simple calculation in their broader assessments of individual investment managers.

The term originates from baseball, where the batting average represents the percentage of a player's hits to at bats. While a season batting average of .300 (30%) or higher is considered an excellent achievement in baseball, the same cannot be said for investing. A batting average of 50% is used as a minimum threshold for measuring investment success.

Batting Average vs. Information Ratio (IR)

The information ratio (IR) is a similar measure of the success (or failure) of money managers. The IR measures portfolio returns beyond the returns of the benchmark compared to the volatility of those returns. The IR not only measures the investment manager's ability to generate high returns relative to the benchmark but it also endeavors to identify the manager's performance consistency.

The calculation includes a tracking error that shows how consistently the manager is able to achieve portfolio returns that track the index. A low tracking error means the manager consistently beats the index performance, while a high tracking error signals the manager's returns are more volatile and not consistently beating the benchmark.

However, the IR does not easily string together a series of successes or failures, which are helpful when assessing final investment outcomes. The batting average overcomes this shortcoming by answering: Does an investment manager win or lose most investment bets?

The information ratio and the batting average are two commonly quoted measures of investment success, but these measures have shortcomings. The IR contains no information about higher moments, and the batting average contains only directional information.

Limitations of Batting Average

More specifically, the batting average suffers from two primary limitations. First, the batting average focuses only on returns and does not take into consideration the level of risk taken by a manager in achieving returns.

Second, the batting average does not factor in the scale of any potential outperformance. A manager might outperform the benchmark by, say, 0.1% for 10 months, but in the 11th month fall short of the benchmark by 3.50%. In such a case the batting average would be 90.90%, but the manager would have dramatically underperformed their benchmark.

Famed investor Warren Buffet is fond of using baseball analogies when talking about investing and cautions investors not to swing at every pitch (that is, investment), but instead focus on investing within your circle of competence, a concept he first described in his 1996 shareholder letter.

Special Considerations

Over time other baseball references have made their way into the world of investing. In his book, One Up on Wall Street, legendary fund manager Peter Lynch introduces the term tenbagger, which refers to an investment that returns ten times its original purchase price or has the potential to do so. An avid baseball fan, Lynch came up with the phrase because "bag" is baseball slang for "base." To score a tenbagger is like hitting two home runs and a double, or the investing equivalent of racking up a very impressive gain.