Guide · US Mid Cap
Best mid-cap ETFs
A mid-cap ETF owns the band of US companies below the large-cap names and above small-caps. Unlike the S&P 500 or total-market categories, the major index vendors disagree about where that band starts and stops — an S&P 400 fund, a CRSP mid-cap fund, and a Russell Midcap fund hold meaningfully different lists. Mid-caps are already inside every total-market fund at market weight, so a dedicated mid-cap fund is either an overweight on top of a total-market core or one leg of a build-your-own completion structure alongside separate large- and small-cap funds.
How the scoring ranks these funds
Mid-cap blend is the highest-scoring category in the catalog — a mean composite just above 90 across 14 funds. The blend funds at the top combine 3–5 basis-point fees with deep liquidity and low top-10 concentration (8–10.5% for the leaders, versus 30%+ in many large-cap funds). The category also includes mid-cap growth and value variants, which score lower mainly on fee and concentration; the leaderboard mixes both.
See the methodology for the full formula behind each sub-score.
Top picks
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96
composite / 100
The highest composite in the category, effectively three-way tied with SCHM and VO. State Street's low-cost "portfolio" line gives S&P MidCap 400 exposure at 3 basis points — the cheapest route to that index. Much smaller than IJH but the same ~400 names.
- Expense
- 0.030%
- AUM
- $18.39B
- Issuer
- State Street
- Detail
- SPMD page →
-
96
composite / 100
Vanguard's mid-cap fund and the largest in the category ($220B+, well ahead of IJH). Tracks the CRSP US Mid Cap Index — a ~300-name band that reaches further up the cap spectrum than the S&P 400, so its average holding is larger than the other funds here. 3 basis points.
- Expense
- 0.030%
- AUM
- $223.97B
- Issuer
- Vanguard
- Detail
- VO page →
-
96
composite / 100
Schwab's mid-cap fund, tracking the Dow Jones U.S. Mid-Cap Total Stock Market Index — roughly 500 names, a third index family distinct from both CRSP and S&P. 4 basis points; commonly held in accounts consolidated at Schwab and commonly used as a third index family in TLH rotations.
- Expense
- 0.030%
- AUM
- $15.32B
- Issuer
- Schwab
- Detail
- SCHM page →
-
96
composite / 100
iShares' S&P MidCap 400 fund and the second-largest in the category at ~$124B. 5 basis points. The S&P 400 is committee-maintained with a profitability requirement and excludes everything in the S&P 500, which makes it the natural completion index next to an S&P 500 fund.
- Expense
- 0.050%
- AUM
- $124.33B
- Issuer
- iShares
- Detail
- IJH page →
-
90
composite / 100
Tracks the Russell Midcap Index — the smallest ~800 names of the Russell 1000, the broadest mid-cap definition of the group and the standard benchmark for active mid-cap managers. The 18-basis-point fee is what costs it on the composite relative to the funds above.
- Expense
- 0.18%
- AUM
- $56.98B
- Issuer
- iShares
- Detail
- IWR page →
Also in the category
Other funds in the same category, ranked by composite score.
The indexes disagree about what "mid-cap" means
The S&P MidCap 400 is a committee-selected list of 400 names with a profitability requirement, defined explicitly as the band below the S&P 500. The CRSP US Mid Cap Index (VO) is a pure-rules band of roughly 300 names that overlaps into territory the S&P committee considers large-cap. The Russell Midcap Index (IWR) is the bottom ~800 of the Russell 1000, the widest definition of the three. The result is that mid-cap funds are far less interchangeable than total-market or S&P 500 funds — the compare pages show the holdings overlap between any pair directly. The different index families are also the standard line of argument for these funds not being "substantially identical" under wash-sale rules, which is why they are commonly cited as TLH partners for one another.
Alongside a total-market fund: overweight, not completion
A total-market fund already owns every mid-cap name at its market-cap weight, so holding VO next to VTI does not add new companies — it raises the portfolio's mid-cap weight above market weight. That is a deliberate size tilt, not extra diversification. The clean completion structure is the S&P family: the 500, 400, and 600 indexes are mutually exclusive, so an S&P 500 fund plus IJH or SPMD reconstructs broad-market coverage with independent control over the size weights and no double-counted holdings. None of the lazy portfolios on this site carry a dedicated mid-cap slot; they reach mid-caps through total-market funds.
MDY, the original mid-cap ETF
MDY is the 1995 SPDR listing that established the S&P 400 as an investable index, and it remains heavily traded. It is structured as a unit investment trust — the same wrapper as SPY — which cannot reinvest dividends internally between distributions, and it charges 23 basis points. SPMD and IJH hold the same ~400 names at 3 and 5 basis points in the standard open-end ETF structure, which is why MDY sits well down this leaderboard despite tracking the identical index.
Guide. Picks come from the live PlainIndex composite for this category; editorial commentary on each pick is hand-written. Re-pulled with every catalog refresh.
PlainIndex publishes data and editorial commentary — nothing here is personalized investment advice. Read the methodology for how the scores referenced here are computed.