CPST vs. SMAX

Last updated Apr 14, 2026

CPST (Calamos S&P 500 Structured Alt Protection ETF - September) and SMAX (iShares Large Cap Max Buffer Sep ETF) are both Defined Outcome funds. CPST is passively managed, while SMAX is actively managed. Over the past year, CPST returned 9.21% vs 10.39% for SMAX. A 0.77 correlation means they provide meaningful diversification when combined. CPST charges 0.69%/yr vs 0.50%/yr for SMAX.

Performance

CPST vs. SMAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Calamos S&P 500 Structured Alt Protection ETF - September (CPST) and iShares Large Cap Max Buffer Sep ETF (SMAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, CPST achieves a 1.02% return, which is significantly lower than SMAX's 1.11% return.

CPST

• 1D: 0.13%
• 1M: 0.92%
• YTD: 1.02%
• 6M: 2.02%
• 1Y: 9.21%
• 3Y*: —
• 5Y*: —
• 10Y*: —

SMAX

• 1D: 0.28%
• 1M: 1.21%
• YTD: 1.11%
• 6M: 2.58%
• 1Y: 10.39%
• 3Y*: —
• 5Y*: —
• 10Y*: —

*Multi-year figures are annualized to reflect compound growth (CAGR)

CPST vs. SMAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024
CPST Calamos S&P 500 Structured Alt Protection ETF - September	1.02%	6.73%	1.20%
SMAX iShares Large Cap Max Buffer Sep ETF	1.11%	8.01%	1.02%

Correlation

The correlation between CPST and SMAX is 0.76, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.76
Correlation (All Time) Calculated using the full available price history since Oct 2, 2024	0.77

The correlation between CPST and SMAX has been stable across timeframes, ranging from 0.76 to 0.77 — a consistent structural relationship.

Return for Risk

CPST vs. SMAX — Risk / Return Rank

Compare risk-adjusted metric ranks to identify better-performing investments over the past 12 months.

CPST

CPST Risk / Return Rank: 94
CPST Sharpe Ratio Rank: 91
CPST Sortino Ratio Rank: 96
CPST Omega Ratio Rank: 96
CPST Calmar Ratio Rank: 92
CPST Martin Ratio Rank: 96

SMAX

SMAX Risk / Return Rank: 93
SMAX Sharpe Ratio Rank: 92
SMAX Sortino Ratio Rank: 95
SMAX Omega Ratio Rank: 95
SMAX Calmar Ratio Rank: 89
SMAX Martin Ratio Rank: 95

The rank (0–100) shows how this investment's returns compare to the risk taken. Higher = better. Based on the past 12 months of data, combining Sharpe, Sortino, and other metrics used by quantitative funds and institutional investors.

CPST vs. SMAX - 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 iShares Large Cap Max Buffer Sep ETF (SMAX). 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.

	CPST	SMAX	Difference
Sharpe ratio Return per unit of total volatility	3.40	3.46	-0.06
Sortino ratio Return per unit of downside risk	5.87	5.42	+0.45
Omega ratio Gain probability vs. loss probability	1.81	1.76	+0.05
Calmar ratio Return relative to maximum drawdown	6.25	5.78	+0.47
Martin ratio Return relative to average drawdown	30.44	29.92	+0.52
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

CPST vs. SMAX - Sharpe Ratio Comparison

The current CPST Sharpe Ratio is 3.40, which is comparable to the SMAX Sharpe Ratio of 3.46. The chart below compares the historical Sharpe Ratios of CPST and SMAX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Sharpe Ratios by Period

	CPST	SMAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	3.40	3.46	-0.06
Sharpe Ratio (All Time) Calculated using the full available price history	1.82	1.76	+0.06

Drawdowns

CPST vs. SMAX - Drawdown Comparison

The maximum CPST drawdown since its inception was -3.79%, roughly equal to the maximum SMAX drawdown of -3.90%. Use the drawdown chart below to compare losses from any high point for CPST and SMAX.

Drawdown Indicators

	CPST	SMAX	Difference
Max Drawdown Largest peak-to-trough decline	-3.79%	-3.90%	+0.11%
Max Drawdown (1Y) Largest decline over 1 year	-1.42%	-1.91%	+0.49%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-0.37%	-0.44%	+0.07%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.29%	0.37%	-0.08%

Volatility

CPST vs. SMAX - Volatility Comparison

The current volatility for Calamos S&P 500 Structured Alt Protection ETF - September (CPST) is 1.15%, while iShares Large Cap Max Buffer Sep ETF (SMAX) has a volatility of 1.41%. This indicates that CPST experiences smaller price fluctuations and is considered to be less risky than SMAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	CPST	SMAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.15%	1.41%	-0.26%
Volatility (6M) Calculated over the trailing 6-month period	1.73%	2.20%	-0.47%
Volatility (1Y) Calculated over the trailing 1-year period	2.73%	3.03%	-0.30%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	3.49%	3.80%	-0.31%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	3.49%	3.80%	-0.31%

CPST vs. SMAX - Expense Ratio Comparison

CPST has a 0.69% expense ratio, which is higher than SMAX's 0.50% expense ratio.

Dividends

CPST vs. SMAX - Dividend Comparison

CPST has not paid dividends to shareholders, while SMAX's dividend yield for the trailing twelve months is around 0.97%.

	TTM	2025	2024
CPST Calamos S&P 500 Structured Alt Protection ETF - September	0.00%	0.00%	0.00%
SMAX iShares Large Cap Max Buffer Sep ETF	0.97%	0.98%	0.27%