CPST vs. APRB
CPST (Calamos S&P 500 Structured Alt Protection ETF - September) and APRB (Aptus April Buffer ETF) are both Defined Outcome funds. CPST is passively managed, while APRB is actively managed. A 0.80 correlation means they provide meaningful diversification when combined. CPST charges 0.69%/yr vs 0.25%/yr for APRB.
Performance
CPST vs. APRB - Performance Comparison
Loading charts...
Returns By Period
In the year-to-date period, CPST achieves a 2.69% return, which is significantly lower than APRB's 4.53% return.
CPST
- 1D
- -0.14%
- 1M
- 0.31%
- YTD
- 2.69%
- 6M
- 2.68%
- 1Y
- 7.04%
- 3Y*
- —
- 5Y*
- —
- 10Y*
- —
APRB
- 1D
- -0.22%
- 1M
- 0.19%
- YTD
- 4.53%
- 6M
- 4.23%
- 1Y
- —
- 3Y*
- —
- 5Y*
- —
- 10Y*
- —
CPST vs. APRB - Yearly Performance Comparison
| 2026 (YTD) | 2025 | |
|---|---|---|
CPST Calamos S&P 500 Structured Alt Protection ETF - September | 2.69% | 0.99% |
APRB Aptus April Buffer ETF | 4.53% | 2.48% |
Correlation
The correlation between CPST and APRB is 0.80, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.
| Correlation | |
|---|---|
Correlation (All Time) Calculated using the full available price history since Oct 14, 2025 | 0.80 |
Compare stocks, funds, or ETFs
Search for stocks, ETFs, and funds for a quick comparison or use the comparison tool for more options.
Return for Risk
CPST vs. APRB — Risk / Return Rank
CPST
APRB
Risk / return metrics aren't available yet — we need at least 12 months of trading data to calculate them.
CPST vs. APRB - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for Calamos S&P 500 Structured Alt Protection ETF - September (CPST) and Aptus April Buffer ETF (APRB). Risk-adjusted metrics are performance indicators that assess an investment's returns in relation to its risk, enabling a more accurate comparison of different investment options.
Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.
| CPST | APRB | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | — | — | |
| Sortino ratioReturn per unit of downside risk | — | — | |
| Omega ratioGain probability vs. loss probability | 1.76 | — | — |
| Calmar ratioReturn relative to maximum drawdown | 4.98 | — | — |
| Martin ratioReturn relative to average drawdown | 26.85 | — | — |
Loading charts...
Drawdowns
CPST vs. APRB - Drawdown Comparison
The maximum CPST drawdown since its inception was -3.79%, smaller than the maximum APRB drawdown of -4.59%. Use the drawdown chart below to compare losses from any high point for CPST and APRB.
Loading charts...
Drawdown Indicators
| CPST | APRB | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -3.79% | -4.59% | +0.80% |
Max Drawdown (1Y)Largest decline over 1 year | -1.42% | — | — |
Current DrawdownCurrent decline from peak | -0.14% | -0.45% | +0.31% |
Average DrawdownAverage peak-to-trough decline | -0.34% | -0.71% | +0.37% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.26% | — | — |
Volatility
CPST vs. APRB - Volatility Comparison
Loading charts...
Volatility by Period
| CPST | APRB | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 0.46% | — | — |
Volatility (6M)Calculated over the trailing 6-month period | 1.61% | — | — |
Volatility (1Y)Calculated over the trailing 1-year period | 2.10% | 5.97% | -3.87% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 3.34% | 5.97% | -2.63% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 3.34% | 5.97% | -2.63% |
CPST vs. APRB - Expense Ratio Comparison
CPST has a 0.69% expense ratio, which is higher than APRB's 0.25% expense ratio.
Dividends
CPST vs. APRB - Dividend Comparison
Neither CPST nor APRB has paid dividends to shareholders.
Frequently Asked Questions
CPST and APRB have a correlation of 0.80, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
On fees, APRB is cheaper at 0.25% per year. The better choice depends on whether you care most about return, fees, risk, or income.
APRB is cheaper with a 0.25% expense ratio, compared with 0.69% for CPST.
CPST and APRB have nearly identical dividend yields, around 0.00%.
They also come from different issuers: Calamos and Aptus Capital Advisors. Their fees differ too: 0.69% for CPST and 0.25% for APRB.
Find the right allocation for CPST and APRB
Add both to a portfolio and optimize allocations for your target — whether that's maximizing returns, minimizing drawdowns, or balancing risk across holdings.
Open Portfolio Optimizer