MDY
US Mid CapState Street SPDR S&P MIDCAP 400 ETF Trust
State Street·Tracks S&P MidCap 400 Index·Inception May 4, 1995
Composite score
Based on a 0.23% expense ratio.
Based on $26.25B in net assets.
Top-10 holdings represent 7.9% of net assets.
US Mid Cap base · ETF wrapper · 1.03% TTM yield.
Tracking error vs. the largest catalog peer tracking the same index. Not yet part of the composite — see methodology.
The composite is a weighted average of the four core sub-scores above (cost, tax efficiency, liquidity, concentration). Missing sub-scores fall back to the per-category median when the category has at least 50% data coverage, so funds without (e.g.) parsed N-PORT holdings aren't accidentally boosted by renormalization. Tracking quality is shown where computable but isn't currently part of the composite weighting. Seemethodologyfor formulas, thetracking-qualitypartial-coverage rationale, and the dimensions we deliberatelydon't score(methodology v0.5.1).
Use MDY in our tools
Tool · Look-through
See what MDY actually holds, in a portfolio
Add your other funds and weights; every underlying position is summed across the basket.
Tool · Cost
Compare MDY's fee against another fund
Compounds the 0.23% expense ratio against a peer over decades.
Tool · Overlap
Compare MDY's holdings with peers
Pairwise holdings heatmap, pre-loaded with similar US Mid Cap funds.
Tool · TLH
Find a tax-loss harvesting partner for MDY
Ranks every catalog fund by holdings overlap, flags wash-sale risk.
Tool · Placement
Where should this fund live across your accounts?
Asset-location optimizer — places each fund in taxable / tax-deferred / Roth.
Top holdings
| # | Holding | Weight |
|---|---|---|
| 1 | Twilio Inc. Class A | 1.00% |
| 2 | Illumina Inc. | 0.87% |
| 3 | TechnipFMC plc | 0.86% |
| 4 | Everpure Inc. Class A | 0.84% |
| 5 | Okta Inc. Class A | 0.82% |
| 6 | U.S. Dollar | 0.80% |
| 7 | ATI Inc | 0.77% |
| 8 | nVent Electric plc | 0.71% |
| 9 | Tenet Healthcare Corporation | 0.64% |
| 10 | Carpenter Technology Corporation | 0.63% |
Holdings from the issuer's published daily file (as of Sep 10, 2026) — this fund does not file usable N-PORT holdings.
Compare MDY with another fund
Or skim the closest-overlap funds below.
Similar ETFs by holdings overlap
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