SPY vs TNDM: Correlation
Measured on weekly returns over the past three years, SPDR S&P 500 ETF Trust (SPY) and Tandem Diabetes Care, Inc. (TNDM) carry a correlation of 0.17, a weak link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are SPY and TNDM?
Over the past 3 years, SPY and TNDM moved with a correlation of 0.17, which is weak. The past 12 months show a weaker link (0.00) than the 3-year average (0.17). Over 5 years the correlation is 0.28, and the annualized covariance of weekly returns is 175.2 %².
Within SPY's tracked universe of 4755 assets, TNDM comes in at #3568 by 3-year correlation. The last year tells two different stories: TNDM led by 54.1 percentage points, +20.6% for SPY against +74.7% for TNDM. Note the risk asymmetry: TNDM runs 4.9 times the annualized volatility of the other leg, so equal-weighting the two is not an equal-risk position.
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.
SPY vs TNDM: side by side
| SPY (SPDR S&P 500 ETF Trust) | TNDM (Tandem Diabetes Care, Inc.) | |
|---|---|---|
| 1-year return | +20.6% | +74.7% |
| 5-year return | +82.4% | -80.9% |
| Volatility (ann.) | 14.5% | 71.1% |
| Beta vs S&P 500 | 1.00 | 0.84 |
| Max drawdown (3Y) | -18.8% | -81.1% |
| Market cap | – | $1.5B |
| P/E (trailing) | – | – |
| Dividend yield | 1.01% | 0.00% |
| Expense ratio | 0.09% | – |
| Assets under management | $795.3B | – |
| Sector / category | ETF · US Large Cap | US Listed |
SPY is a Large Blend fund from State Street Investment Management: $795.3B under management, 504 holdings, a 0.09% expense ratio, a 1.01% trailing dividend yield.
Year-by-year returns
| Year | SPY | TNDM |
|---|---|---|
| 2022 | -18.2% | -70.1% |
| 2023 | +26.2% | -34.2% |
| 2024 | +24.9% | +21.8% |
| 2025 | +17.7% | -39.0% |
| 2026 | +13.7% | -2.6% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are SPY and TNDM good diversifiers for each other?
By historical standards, yes. A correlation of 0.17 means the two rarely move for the same reasons.
FAQ
What is the correlation between SPY and TNDM?
Using weekly returns as of 2026-08-27: 0.17 over 3 years, with 0.00 over the last year and 0.28 over 5 years.
Is TNDM a good diversifier for SPY?
By historical standards, yes. A correlation of 0.17 means the two rarely move for the same reasons.
What does a correlation of 0.17 mean?
A reading of 0.17 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/spy-vs-tndm.json
Markdown for the live badge, attribution link included:
[](https://www.pairbook.io/pair/spy-vs-tndm/)
No key needed, free to use. Full endpoint list in the API documentation.
Related comparisons
Hubs: SPY correlations · TNDM correlations
