CPST vs. OCTB

Last updated Jun 3, 2026

CPST (Calamos S&P 500 Structured Alt Protection ETF - September) and OCTB (Aptus October Buffer ETF) are both Defined Outcome funds. CPST is passively managed, while OCTB is actively managed. Their correlation of 0.83 suggests significant overlap in exposure. CPST charges 0.69%/yr vs 0.25%/yr for OCTB.

Performance

CPST vs. OCTB - 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 Aptus October Buffer ETF (OCTB). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, CPST achieves a 2.67% return, which is significantly lower than OCTB's 6.36% return.

CPST

• 1D: 0.07%
• 1M: 0.82%
• YTD: 2.67%
• 6M: 3.20%
• 1Y: 7.84%
• 3Y*: —
• 5Y*: —
• 10Y*: —

OCTB

• 1D: 0.06%
• 1M: 2.36%
• YTD: 6.36%
• 6M: 7.12%
• 1Y: —
• 3Y*: —
• 5Y*: —
• 10Y*: —

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

CPST vs. OCTB - Yearly Performance Comparison

	2026 (YTD)	2025
CPST Calamos S&P 500 Structured Alt Protection ETF - September	2.67%	1.04%
OCTB Aptus October Buffer ETF	6.36%	2.37%

Correlation

The correlation between CPST and OCTB is 0.83, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (All Time) Calculated using the full available price history since Oct 15, 2025	0.83

Return for Risk

CPST vs. OCTB — 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: 94
CPST Sortino Ratio Rank: 97
CPST Omega Ratio Rank: 96
CPST Calmar Ratio Rank: 90
CPST 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. OCTB - 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 October Buffer ETF (OCTB). 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	OCTB	Difference
Sharpe ratio Return per unit of total volatility	3.66	—	—
Sortino ratio Return per unit of downside risk	6.09	—	—
Omega ratio Gain probability vs. loss probability	1.84	—	—
Calmar ratio Return relative to maximum drawdown	5.58	—	—
Martin ratio Return relative to average drawdown	30.14	—	—
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

Sharpe Ratios by Period

	CPST	OCTB	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	3.66	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	2.02	2.02	0.00

Drawdowns

CPST vs. OCTB - Drawdown Comparison

The maximum CPST drawdown since its inception was -3.79%, smaller than the maximum OCTB drawdown of -4.79%. Use the drawdown chart below to compare losses from any high point for CPST and OCTB.

Drawdown Indicators

	CPST	OCTB	Difference
Max Drawdown Largest peak-to-trough decline	-3.79%	-4.79%	+1.00%
Max Drawdown (1Y) Largest decline over 1 year	-1.42%	—	—
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-0.35%	-0.70%	+0.35%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.26%	—	—

Volatility

Volatility by Period

	CPST	OCTB	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.32%	—	—
Volatility (6M) Calculated over the trailing 6-month period	1.60%	—	—
Volatility (1Y) Calculated over the trailing 1-year period	2.15%	7.22%	-5.07%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	3.37%	7.22%	-3.85%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	3.37%	7.22%	-3.85%

CPST vs. OCTB - Expense Ratio Comparison

CPST has a 0.69% expense ratio, which is higher than OCTB's 0.25% expense ratio.

Dividends

CPST vs. OCTB - Dividend Comparison

Neither CPST nor OCTB has paid dividends to shareholders.

Tickers have no history of dividend payments

Frequently Asked Questions

Can I hold both CPST and OCTB in my portfolio?

CPST and OCTB have a correlation of 0.83, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which ETF is better, CPST or OCTB?

On fees, OCTB is cheaper at 0.25% per year. The better choice depends on whether you care most about return, fees, risk, or income.

Which ETF is cheaper, CPST or OCTB?

OCTB is cheaper with a 0.25% expense ratio, compared with 0.69% for CPST.

Which ETF pays a higher dividend yield, CPST or OCTB?

CPST and OCTB have nearly identical dividend yields, around 0.00%.

What is the main difference between CPST and OCTB?

They also come from different issuers: Calamos and Aptus Capital Advisors. Their fees differ too: 0.69% for CPST and 0.25% for OCTB.