PTCT vs SPY: Correlation
Measured on weekly returns over the past three years, PTC Therapeutics, Inc. (PTCT) and SPDR S&P 500 ETF Trust (SPY) carry a correlation of 0.34, a moderate link.
Data as of 2026-08-27 · refreshed every trading day · weekly returns · methodology
How correlated are PTCT and SPY?
Over the past 3 years, PTCT and SPY moved with a correlation of 0.34, which is moderate. The relationship has been stable: the 1-year correlation (0.31) sits close to the 3-year figure. Over 5 years the correlation is 0.33, and the annualized covariance of weekly returns is 260.1 %².
SPY is close to the least connected end of PTCT's tracked universe, ranking #7 of 11. The last year tells two different stories: PTCT led by 23.7 percentage points, +44.3% for PTCT against +20.6% for SPY. Risk is not evenly split, since PTCT carries 3.6 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.
PTCT vs SPY: side by side
| PTCT (PTC Therapeutics, Inc.) | SPY (SPDR S&P 500 ETF Trust) | |
|---|---|---|
| 1-year return | +44.3% | +20.6% |
| 5-year return | +70.4% | +82.4% |
| Volatility (ann.) | 52.5% | 14.5% |
| Beta vs S&P 500 | 1.25 | 1.00 |
| Max drawdown (3Y) | -56.8% | -18.8% |
| Market cap | $6.0B | – |
| P/E (trailing) | – | – |
| Dividend yield | 0.00% | 1.01% |
| Expense ratio | – | 0.09% |
| Assets under management | – | $795.3B |
| Sector / category | US Listed | 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 | PTCT | SPY |
|---|---|---|
| 2022 | -4.2% | -18.2% |
| 2023 | -27.8% | +26.2% |
| 2024 | +63.8% | +24.9% |
| 2025 | +68.3% | +17.7% |
| 2026 | -5.5% | +13.7% |
Calendar-year price returns; the current year is year-to-date as of the data date above.
Are PTCT and SPY good diversifiers for each other?
A fair diversifier. At 0.34, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
FAQ
What is the correlation between PTCT and SPY?
The PTCT/SPY correlation stands at 0.34 on a 3-year window (1 year: 0.31, 5 years: 0.33), computed from weekly returns as of 2026-08-27.
Is SPY a good diversifier for PTCT?
A fair diversifier. At 0.34, enough of each asset's movement is its own that the pair has smoothed outcomes historically.
What does a correlation of 0.34 mean?
Correlation ranges from −1 to +1. Values near +1 mean two assets move together, near 0 that they move independently, and negative values that they tend to move in opposite directions. It measures co-movement, not performance.
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Related comparisons
Hubs: PTCT correlations · SPY correlations
