MDY vs TDY: Correlation
Measured on weekly returns over the past three years, SPDR S&P MidCap 400 ETF (MDY) and Teledyne Technologies (TDY) carry a correlation of 0.58, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are MDY and TDY?
Across a 3-year window, the weekly returns of MDY and TDY correlate at 0.58, moderate. Little has changed lately, as the 1-year reading of 0.49 lands near the 3-year figure. Stretching to 5 years gives 0.63, with an annualized covariance of 208.9 %².
By 3-year correlation, TDY places #213 of the 359 assets tracked against MDY. Twelve-month performance is nearly a tie, at +18.3% for MDY and +15.7% for TDY. Across three years, the rolling one-year figure varied moderately, from 0.38 to 0.70.
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 TDY: side by side
| MDY (SPDR S&P MidCap 400 ETF) | TDY (Teledyne Technologies) | |
|---|---|---|
| 1-year return | +18.3% | +15.7% |
| 5-year return | +47.5% | +36.5% |
| Volatility (ann.) | 16.5% | 22.0% |
| Beta vs S&P 500 | 0.91 | 0.76 |
| Max drawdown (3Y) | -24.0% | -18.8% |
| Market cap | – | $29.0B |
| P/E (trailing) | – | 30.7 |
| Dividend yield | 1.02% | 0.00% |
| Expense ratio | 0.23% | – |
| Assets under management | $26.5B | – |
| Sector / category | ETF · US Small & Mid Cap | Information Technology |
MDY is a Mid-Cap Blend fund from State Street Investment Management: $26.5B under management, 400 holdings, a 0.23% expense ratio, a 1.02% trailing dividend yield.
Year-by-year returns
| Year | MDY | TDY |
|---|---|---|
| 2022 | -13.3% | -8.5% |
| 2023 | +16.1% | +11.6% |
| 2024 | +13.6% | +4.0% |
| 2025 | +7.2% | +10.0% |
| 2026 | +16.4% | +22.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are MDY and TDY good diversifiers for each other?
Only partially. A correlation of 0.58 means MDY and TDY 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 MDY and TDY?
Using weekly returns as of 2026-08-27: 0.58 over 3 years, with 0.49 over the last year and 0.63 over 5 years.
Is TDY a good diversifier for MDY?
Only partially. A correlation of 0.58 means MDY and TDY share most of their swings. Pairing them dampens volatility somewhat, but it will not protect against a common drawdown.
What does a correlation of 0.58 mean?
On the −1 to +1 scale, 0.58 describes how much the two returns move together: +1 is lockstep, 0 is independence, negative values mean opposite directions. It says nothing about which performed better.
Use this data
$ curl https://www.pairbook.io/api/v1/pairs/mdy-vs-tdy.json
Embed this badge (it refreshes with the data), with attribution:
[](https://www.pairbook.io/pair/mdy-vs-tdy/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: MDY correlations · TDY correlations
