Updated August 10, 2026. Quick answer. The Morningstar Style Box is a nine-square grid that classifies a stock or fund by size (small, mid, large) on one axis and investment style (value, blend/core, growth) on the other. Introduced in 1992 by Morningstar’s Don Phillips and John Rekenthaler, its structure hasn’t changed since — it’s one of the most widely reused classification tools in fund research, appearing on fund fact sheets across the industry, not just on Morningstar’s own site.
The nine boxes
| Value | Blend | Growth | |
|---|---|---|---|
| Large | Large Value | Large Blend | Large Growth |
| Mid | Mid Value | Mid Blend | Mid Growth |
| Small | Small Value | Small Blend | Small Growth |
A fund’s placement (usually shown as one highlighted square) marks its “center of gravity” — where its holdings, on average, actually sit — not a rule about what it’s allowed to hold.
The size axis: what “large,” “mid,” and “small” mean here
The vertical axis sorts by market capitalization. For an individual stock, the box shown reflects “core” style (neither value nor growth characteristics dominate) in the middle column; for a fund, the middle column represents a blend — a genuine mixture of value and growth holdings, or a portfolio of stocks that individually show both characteristics at once.
The style axis: value, blend, growth
A growth-oriented holding is one the assessment expects to grow sales and earnings faster than the broader market; a value-oriented holding is one considered underpriced relative to its fundamentals, with the market expected to eventually recognize that. Blend sits between the two — a genuine mixture, not a third distinct style.
Why it still matters when comparing funds
Two funds sitting in different style-box squares can post very different returns in the same year for reasons that have nothing to do with which fund is “better” — growth and value segments of the market rotate in and out of favor independently. Confirming two funds actually occupy the same or a similar box is part of making sure you’re comparing like to like — see our how to compare two mutual funds guide for the full comparison workflow.
Sources
Wikipedia, “Morningstar Style Box” (accessed August 2026), summarizing the tool’s 1992 introduction, structure, and named developers. This describes a stable, long-standing classification structure, not a claim about any specific fund’s current placement.
The Style Box describes historical portfolio composition, not a prediction of future returns.
See a fund’s current style-box placement next to its category
Morningstar Investor shows a fund’s current style-box square alongside its expense ratio and category peers.
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