IOSP vs MDY: Correlation
Innospec Inc. (IOSP) and SPDR S&P MidCap 400 ETF (MDY) show a strong relationship: their 3-year correlation of weekly returns is 0.73.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are IOSP and MDY?
Across a 3-year window, the weekly returns of IOSP and MDY correlate at 0.73, strong. The relationship has been stable: the 1-year correlation (0.66) sits close to the 3-year figure. Stretching to 5 years gives 0.66, with an annualized covariance of 321.6 %².
In IOSP's tracked universe of 35 assets, MDY sits right near the top at #1. Over the last 12 months MDY came out ahead by 7.0 percentage points (+11.3% against +18.3%). Risk is not evenly split, since IOSP carries 1.6 times the volatility of the other side.
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.
IOSP vs MDY: side by side
| IOSP (Innospec Inc.) | MDY (SPDR S&P MidCap 400 ETF) | |
|---|---|---|
| 1-year return | +11.3% | +18.3% |
| 5-year return | +10.2% | +47.5% |
| Volatility (ann.) | 26.6% | 16.5% |
| Beta vs S&P 500 | 0.94 | 0.91 |
| Max drawdown (3Y) | -48.4% | -24.0% |
| Market cap | $2.3B | – |
| P/E (trailing) | 19.5 | – |
| Dividend yield | 1.87% | 1.02% |
| Expense ratio | – | 0.23% |
| Assets under management | – | $26.5B |
| Sector / category | US Listed | ETF · US Small & Mid Cap |
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.
Year-by-year returns
| Year | IOSP | MDY |
|---|---|---|
| 2022 | +15.2% | -13.3% |
| 2023 | +21.5% | +16.1% |
| 2024 | -9.6% | +13.6% |
| 2025 | -28.9% | +7.2% |
| 2026 | +26.0% | +16.4% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are IOSP and MDY good diversifiers for each other?
Only partially. A correlation of 0.73 means IOSP and MDY share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
FAQ
What is the correlation between IOSP and MDY?
As of 2026-08-27, the correlation of weekly returns between IOSP and MDY is 0.73 over 3 years, 0.66 over 1 year and 0.66 over 5 years.
Is MDY a good diversifier for IOSP?
Only partially. A correlation of 0.73 means IOSP and MDY share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.73 mean?
A reading of 0.73 sits on a scale from −1 (opposite moves) through 0 (unrelated) to +1 (identical moves). Correlation captures direction, not magnitude or performance.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/iosp-vs-mdy.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/iosp-vs-mdy/)
Free with attribution; caching and terms are described in the API documentation.
Related comparisons
Hubs: IOSP correlations · MDY correlations
