Most widely accepted indexes consider value and growth stocks to be complements of each other. By this definition, a growth stock is anything that is not a value stock, and a value stock is anything that is not a growth stock. The delineation typically depends upon a single factor, such as price/book ratio, or perhaps a combination of several factors blended into a single style rank for every stock, as depicted in the spectrum below:
Active managers do not believe their world is flat. A value manager may hold a stock owned by a growth manager. The stock may fully satisfy the requirements of both. A value manager might require that a stock have a low price/earnings ratio, for example, but would certainly not be dismayed to see that it also enjoyed strong growth prospects. Nor would a growth manager exclude a stock that met his or her requirements for growth just because it sported a low valuation.
Using their own independent criteria, value and growth managers occasionally fish from the same pond. Conversely, some stocks are attractive to neither. For active managers, stocks don't fall into rank on a simple line like that shown above; instead, the delineation between value and growth is two-dimensional.
Value managers emphasize a company's fundamentals relative to its current price, including price/earnings, price/book, price/sales and dividend/price (yield) ratios. They analyze companies based on these criteria and subject those that pass a certain hurdle to further analysis. Growth managers, by contrast, place the primary emphasis on characteristics such as earnings growth, sales growth, and margin growth. Working independently, value and growth managers analyze companies along their own growth or value spectra. Their combined view, with the dotted lines demarcating each category's hurdle rates, is shown in the graphic below.
In two dimensions, some stocks are pure value or growth, others are both value and growth, while still others appeal to neither growth nor value managers. Based on a stock's price ratios, for example, a value manager might conclude that it is a value stock. Evaluating its sales and earnings growth, a growth manager might conclude that the same security is a growth stock. Using two distinct methodologies, both managers determine that the stock is a component of their universe. Style-based indexes should reflect this reality, rather than forcing a stock into one category or the other. Consequently, growth and value indexes, as subsets of broader indexes, should not be perfect complements.
Given this design, a combination of value and growth index funds will result in some overlap in holdings. It will also exclude some stocks. But that is true of actively-managed portfolios as well. As in the case of market-cap-oriented funds, the combination of actively-managed growth and value funds does not yield a complete non-overlapping portfolio. If the style indexes are to be good benchmarks, they won't necessarily be perfect complements of each other. Index investors who want to combine value and growth should simply invest in a blended index.
This methodology would also allow us to create deep-value and aggressive-growth indexes by setting higher hurdles for those extreme styles. And as with the capitalization indexes, there should be bands around the growth and value demarcations.