ZST.TO vs. PSA.TO

Last updated Jun 4, 2026

ZST.TO (BMO Ultra Short-Term Bond ETF) and PSA.TO (Purpose High Interest Savings Fund) are both exchange-traded funds - ZST.TO is a Canadian Government Bonds fund actively managed by BMO, while PSA.TO is a Money Market fund actively managed by Purpose Investments. Both are actively managed. Over the past 10 years, ZST.TO returned 2.34%/yr vs 2.25%/yr for PSA.TO. At a 0.09 correlation, their price movements are largely independent. Both charge a 0.17% expense ratio.

Performance

ZST.TO vs. PSA.TO - Performance Comparison

The chart below illustrates the hypothetical performance of a CA$10,000 investment in BMO Ultra Short-Term Bond ETF (ZST.TO) and Purpose High Interest Savings Fund (PSA.TO). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, ZST.TO achieves a 1.08% return, which is significantly higher than PSA.TO's 0.89% return. Both investments have delivered pretty close results over the past 10 years, with ZST.TO having a 2.34% annualized return and PSA.TO not far behind at 2.25%.

ZST.TO

• 1D: 0.02%
• 1M: 0.25%
• YTD: 1.08%
• 6M: 0.26%
• 1Y: 1.68%
• 3Y*: 3.84%
• 5Y*: 2.95%
• 10Y*: 2.34%

PSA.TO

• 1D: 0.00%
• 1M: 0.17%
• YTD: 0.89%
• 6M: 1.08%
• 1Y: 2.35%
• 3Y*: 3.73%
• 5Y*: 3.17%
• 10Y*: 2.25%

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

ZST.TO vs. PSA.TO - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
ZST.TO BMO Ultra Short-Term Bond ETF	1.08%	2.03%	5.16%	5.33%	1.19%	0.22%	1.74%	2.36%	1.95%	1.43%
PSA.TO Purpose High Interest Savings Fund	0.89%	2.64%	4.56%	5.12%	2.34%	0.60%	0.93%	2.22%	1.65%	1.09%

Correlation

The correlation between ZST.TO and PSA.TO is -0.16, meaning they tend to move in opposite directions. This is especially valuable for risk management - when one declines, the other has historically tended to hold steady or rise.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	-0.16
Correlation (3Y) Calculated over the trailing 3-year period	0.13
Correlation (5Y) Calculated over the trailing 5-year period	0.16
Correlation (10Y) Calculated over the trailing 10-year period	0.13
Correlation (All Time) Calculated using the full available price history since Oct 16, 2013	0.09

The correlation between ZST.TO and PSA.TO shifts across timeframes, from -0.16 (1 year) to 0.16 (5 years), reflecting how their relationship changes across market environments.

Return for Risk

ZST.TO vs. PSA.TO — Risk / Return Rank

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

ZST.TO

ZST.TO Risk / Return Rank: 47
ZST.TO Sharpe Ratio Rank: 44
ZST.TO Sortino Ratio Rank: 30
ZST.TO Omega Ratio Rank: 96
ZST.TO Calmar Ratio Rank: 34
ZST.TO Martin Ratio Rank: 30

PSA.TO

PSA.TO Risk / Return Rank: 100
PSA.TO Sharpe Ratio Rank: 99
PSA.TO Sortino Ratio Rank: 100
PSA.TO Omega Ratio Rank: 100
PSA.TO Calmar Ratio Rank: 100
PSA.TO Martin Ratio Rank: 100

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.

ZST.TO vs. PSA.TO - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for BMO Ultra Short-Term Bond ETF (ZST.TO) and Purpose High Interest Savings Fund (PSA.TO). 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.

	ZST.TO	PSA.TO	Difference
Sharpe ratio: Return per unit of total volatility	1.56	10.34	-8.78
Sortino ratio: Return per unit of downside risk	1.64	28.20	-26.56
Omega ratio: Gain probability vs. loss probability	1.83	6.27	-4.45
Calmar ratio: Return relative to maximum drawdown	1.68	117.76	-116.08
Martin ratio: Return relative to average drawdown	4.51	422.79	-418.28
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

ZST.TO vs. PSA.TO - Sharpe Ratio Comparison

The current ZST.TO Sharpe Ratio is 1.56, which is lower than the PSA.TO Sharpe Ratio of 10.34. The chart below compares the historical Sharpe Ratios of ZST.TO and PSA.TO, 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

	ZST.TO	PSA.TO	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.56	10.34	-8.78
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	4.12	11.66	-7.54
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	3.30	9.68	-6.39
Sharpe Ratio (All Time) Calculated using the full available price history	1.81	9.26	-7.45

Drawdowns

ZST.TO vs. PSA.TO - Drawdown Comparison

The maximum ZST.TO drawdown since its inception was -1.06%, which is greater than PSA.TO's maximum drawdown of -0.04%. Use the drawdown chart below to compare losses from any high point for ZST.TO and PSA.TO.

Drawdown Indicators

	ZST.TO	PSA.TO	Difference
Max Drawdown Largest peak-to-trough decline	-1.06%	-0.04%	-1.02%
Max Drawdown (1Y) Largest decline over 1 year	-1.01%	-0.02%	-0.99%
Max Drawdown (3Y) Largest decline over 3 years	-1.01%	-0.02%	-0.99%
Max Drawdown (5Y) Largest decline over 5 years	-1.01%	-0.04%	-0.97%
Max Drawdown (10Y) Largest decline over 10 years	-1.06%	-0.04%	-1.02%
Current Drawdown Current decline from peak	-0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-0.13%	-0.00%	-0.13%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.37%	0.01%	+0.36%

Volatility

ZST.TO vs. PSA.TO - Volatility Comparison

BMO Ultra Short-Term Bond ETF (ZST.TO) has a higher volatility of 0.08% compared to Purpose High Interest Savings Fund (PSA.TO) at 0.06%. This indicates that ZST.TO's price experiences larger fluctuations and is considered to be riskier than PSA.TO based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	ZST.TO	PSA.TO	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.08%	0.06%	+0.02%
Volatility (6M) Calculated over the trailing 6-month period	1.05%	0.16%	+0.89%
Volatility (1Y) Calculated over the trailing 1-year period	1.08%	0.23%	+0.85%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	0.72%	0.27%	+0.45%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	0.71%	0.24%	+0.47%

ZST.TO vs. PSA.TO - Expense Ratio Comparison

Both ZST.TO and PSA.TO have an expense ratio of 0.17%, making them cost-effective options compared to the broader market, where average expense ratios typically range from 0.3% to 0.9%.

Dividends

ZST.TO vs. PSA.TO - Dividend Comparison

ZST.TO's dividend yield for the trailing twelve months is around 2.55%, more than PSA.TO's 2.33% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
PSA.TO Purpose High Interest Savings Fund	2.33%	2.61%	4.47%	5.05%	2.26%	0.59%	0.94%	2.18%	1.66%	1.07%	0.99%	1.07%
ZST.TO BMO Ultra Short-Term Bond ETF	2.55%	2.82%	4.65%	4.79%	2.75%	2.29%	2.65%	2.82%	3.43%	4.05%	3.92%	3.90%

Frequently Asked Questions

Can I hold both ZST.TO and PSA.TO in my portfolio?

ZST.TO and PSA.TO have a correlation of -0.16, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which ETF is better, ZST.TO or PSA.TO?

Both ETFs have the same 0.17% expense ratio. The better choice depends on whether you care most about return, fees, risk, or income.

Which ETF is cheaper, ZST.TO or PSA.TO?

ZST.TO and PSA.TO have the same expense ratio: 0.17% per year.

What is the main difference between ZST.TO and PSA.TO?

ZST.TO is categorized as Canadian Government Bonds, while PSA.TO is Money Market. They also come from different issuers: BMO and Purpose Investments.