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 $28.05B in net assets.
Top-10 holdings represent 7.8% of net assets.
US Mid Cap base · ETF wrapper · 1.02% 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. See methodology for formulas, the tracking-quality partial-coverage rationale, and the dimensions we deliberately don't score (methodology v0.5.1).
Use MDY in our tools
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 | 0.92% |
| 2 | U.S. Dollar | 0.85% |
| 3 | TechnipFMC plc | 0.83% |
| 4 | Illumina Inc. | 0.80% |
| 5 | Carpenter Technology Corporation | 0.80% |
| 6 | Curtiss-Wright Corporation | 0.77% |
| 7 | nVent Electric plc | 0.73% |
| 8 | Okta Inc. Class A | 0.72% |
| 9 | ATI Inc | 0.72% |
| 10 | XPO Inc. | 0.69% |
Holdings from the issuer's published daily file (as of Jul 14, 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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