CMCSA vs SPY: Correlation
How closely do Comcast (CMCSA) and SPDR S&P 500 ETF Trust (SPY) trade together? Their weekly returns over three years give a correlation of 0.29, which is weak.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are CMCSA and SPY?
Over the past 3 years, CMCSA and SPY moved with a correlation of 0.29, which is weak. Lately the two have drifted apart, with the 1-year correlation at 0.15 versus 0.29 over 3 years. Over 5 years the correlation is 0.39, and the annualized covariance of weekly returns is 99.8 %².
By 3-year correlation, SPY places #26 of the 39 assets tracked against CMCSA. Correlation aside, the last 12 months split them widely, with SPY ahead by 33.2 points (-12.6% versus +20.6%). This link changes with the market regime, having swung between -0.06 and 0.72 on a rolling one-year basis. Note the risk asymmetry: CMCSA runs 1.6 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.
CMCSA vs SPY: side by side
| CMCSA (Comcast) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | -12.6% | +20.6% |
| 5-year return | -44.5% | +82.4% |
| Volatility (ann.) | 23.8% | 14.5% |
| Beta vs S&P 500 | 0.48 | 1.00 |
| Max drawdown (3Y) | -44.9% | -18.8% |
| Market cap | $93.7B | – |
| P/E (trailing) | 8.7 | – |
| Dividend yield | 4.85% | 1.01% |
| Expense ratio | – | 0.09% |
| Assets under management | – | $795.3B |
| Sector / category | Communication Services | ETF · US Large Cap |
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 | CMCSA | SPY |
|---|---|---|
| 2022 | -28.7% | -18.2% |
| 2023 | +29.1% | +26.2% |
| 2024 | -11.8% | +24.9% |
| 2025 | -17.3% | +17.7% |
| 2026 | -2.2% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Fund exposure
A structural note: 0.15% of SPY is CMCSA itself, so the fund partly moves with the stock by construction.
Are CMCSA and SPY good diversifiers for each other?
Reasonably. At 0.29, CMCSA and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
FAQ
What is the correlation between CMCSA and SPY?
As of 2026-08-27, the correlation of weekly returns between CMCSA and SPY is 0.29 over 3 years, 0.15 over 1 year and 0.39 over 5 years.
Is SPY a good diversifier for CMCSA?
Reasonably. At 0.29, CMCSA and SPY keep a meaningful degree of independence, and combining them has historically reduced portfolio volatility.
What does a correlation of 0.29 mean?
A reading of 0.29 sits on a scale from −1 (opposite moves) through 0 (unrelated) to +1 (identical moves). Correlation captures direction, not magnitude or performance.
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Related comparisons
Hubs: CMCSA correlations · SPY correlations
