MDY vs SOXX: Correlation & Overlap
How closely do SPDR S&P MidCap 400 ETF (MDY) and iShares Semiconductor ETF (SOXX) trade together? Their weekly returns over three years give a correlation of 0.65, which is strong. By holdings, the two funds overlap 1.4% by weight.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and SOXX?
Over the past 3 years, MDY and SOXX moved with a correlation of 0.65, which is strong. Recent behaviour matches the longer record: 0.59 over 1 year against 0.65 over 3. Over 5 years the correlation is 0.69, and the annualized covariance of weekly returns is 376.3 %².
By 3-year correlation, SOXX places #118 of the 359 assets tracked against MDY. Correlation aside, the last 12 months split them widely, with SOXX ahead by 91.7 points (+18.3% versus +110.0%). The link looks structural: the rolling one-year correlation barely moved, holding between 0.55 and 0.76. One caveat on sizing: SOXX is 2.1 times as volatile as the other leg, so an equal-dollar split is far from equal-risk.
How is this computed?
Pearson correlation on weekly returns: ρ(A,B) = cov(rA, rB) / (σA · σB), over windows of 52, 156 and 260 weeks. Covariance is annualized (×52) and expressed in %². Full definitions on the methodology page.
MDY vs SOXX: side by side
| MDY (SPDR S&P MidCap 400 ETF) | SOXX (iShares Semiconductor ETF) | |
|---|---|---|
| 1-year return | +18.3% | +110.0% |
| 5-year return | +47.5% | +247.5% |
| Volatility (ann.) | 16.5% | 35.2% |
| Beta vs S&P 500 | 0.91 | 1.93 |
| Max drawdown (3Y) | -24.0% | -41.4% |
| Dividend yield | 1.02% | 0.29% |
| Expense ratio | 0.23% | 0.33% |
| Assets under management | $26.5B | $44.7B |
| Sector / category | ETF · US Small & Mid Cap | ETF · Thematic |
MDY, State Street Investment Management's Mid-Cap Blend fund, carries $26.5B under management, 400 holdings, a 0.23% expense ratio, a 1.02% trailing dividend yield. On the fund side, SOXX sits in the Technology category at iShares, with $44.7B under management, 30 holdings, a 0.33% expense ratio, a 0.29% trailing dividend yield.
Portfolio overlap between MDY and SOXX
The two portfolios are largely distinct. Weighing the shared positions, 1.4% of the two funds is identical, spread across 3 common holdings. That shared book is a large part of why the returns line up.
Largest positions held only by MDY: TWLO (0.95%), P (0.94%), ILMN (0.93%), FTI (0.83%), ATI (0.80%). Only by SOXX: NVDA (8.87%), MU (8.64%), AMD (8.33%), AVGO (7.11%), MRVL (5.34%).
Overlap = sum of the smaller of the two weights across common holdings, from issuer disclosures as of 2026-08-26. Top 3 common positions shown.
Year-by-year returns
| Year | MDY | SOXX |
|---|---|---|
| 2022 | -13.3% | -35.1% |
| 2023 | +16.1% | +67.1% |
| 2024 | +13.6% | +12.9% |
| 2025 | +7.2% | +40.7% |
| 2026 | +16.4% | +74.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and SOXX good diversifiers for each other?
To a limited degree. At 0.65 the two still catch most of the same waves, so the pair smooths returns a little without insulating either from a shared selloff.
FAQ
What is the correlation between MDY and SOXX?
The MDY/SOXX correlation stands at 0.65 on a 3-year window (1 year: 0.59, 5 years: 0.69), computed from weekly returns as of 2026-08-27.
Is SOXX a good diversifier for MDY?
To a limited degree. At 0.65 the two still catch most of the same waves, so the pair smooths returns a little without insulating either from a shared selloff.
How much do MDY and SOXX overlap?
The two funds share 3 holdings amounting to 1.4% of weight, per issuer portfolio files dated 2026-08-26.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/mdy-vs-soxx.json
Drop this badge in a README or notebook; it updates with the data:
[](https://www.pairbook.io/pair/mdy-vs-soxx/)
The core API is free. Terms and every endpoint in the API documentation.
Related comparisons
Hubs: MDY correlations · SOXX correlations
