TAFTX vs. COSIX

Last updated Jun 4, 2026

TAFTX (American Funds Tax-Exempt Fund of California) and COSIX (Columbia Strategic Income Fund) are both mutual funds - TAFTX is a Municipal Bonds fund managed by American Funds, while COSIX is a Nontraditional Bonds fund managed by Columbia. Over the past 10 years, TAFTX returned 2.09%/yr vs 3.57%/yr for COSIX. At a 0.32 correlation, their price movements are largely independent. TAFTX charges 0.57%/yr vs 0.92%/yr for COSIX.

Performance

TAFTX vs. COSIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds Tax-Exempt Fund of California (TAFTX) and Columbia Strategic Income Fund (COSIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, TAFTX achieves a 1.58% return, which is significantly higher than COSIX's 1.35% return. Over the past 10 years, TAFTX has underperformed COSIX with an annualized return of 2.09%, while COSIX has yielded a comparatively higher 3.57% annualized return.

TAFTX

• 1D: 0.18%
• 1M: 0.86%
• YTD: 1.58%
• 6M: 1.91%
• 1Y: 7.46%
• 3Y*: 4.15%
• 5Y*: 0.88%
• 10Y*: 2.09%

COSIX

• 1D: 0.09%
• 1M: 0.65%
• YTD: 1.35%
• 6M: 1.24%
• 1Y: 5.32%
• 3Y*: 6.53%
• 5Y*: 1.87%
• 10Y*: 3.57%

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

TAFTX vs. COSIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
TAFTX American Funds Tax-Exempt Fund of California	1.58%	4.73%	2.31%	5.76%	-9.78%	1.88%	4.43%	7.33%	0.71%	5.96%
COSIX Columbia Strategic Income Fund	1.35%	6.98%	4.50%	9.86%	-11.65%	1.34%	7.12%	10.19%	-0.96%	5.48%

Correlation

The correlation between TAFTX and COSIX is 0.56, 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	0.56
Correlation (3Y) Calculated over the trailing 3-year period	0.63
Correlation (5Y) Calculated over the trailing 5-year period	0.56
Correlation (10Y) Calculated over the trailing 10-year period	0.40
Correlation (All Time) Calculated using the full available price history since Oct 29, 1986	0.32

Over the past year, TAFTX and COSIX have become more correlated (0.56) than their long-term average of 0.32, meaning their price movements have been converging.

Return for Risk

TAFTX vs. COSIX — Risk / Return Rank

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

TAFTX

TAFTX Risk / Return Rank: 67
TAFTX Sharpe Ratio Rank: 80
TAFTX Sortino Ratio Rank: 85
TAFTX Omega Ratio Rank: 89
TAFTX Calmar Ratio Rank: 41
TAFTX Martin Ratio Rank: 39

COSIX

COSIX Risk / Return Rank: 41
COSIX Sharpe Ratio Rank: 40
COSIX Sortino Ratio Rank: 43
COSIX Omega Ratio Rank: 38
COSIX Calmar Ratio Rank: 41
COSIX Martin Ratio Rank: 45

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.

TAFTX vs. COSIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds Tax-Exempt Fund of California (TAFTX) and Columbia Strategic Income Fund (COSIX). 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.

	TAFTX	COSIX	Difference
Sharpe ratio Return per unit of total volatility	2.60	1.83	+0.77
Sortino ratio Return per unit of downside risk	4.06	2.74	+1.32
Omega ratio Gain probability vs. loss probability	1.63	1.33	+0.30
Calmar ratio Return relative to maximum drawdown	2.42	2.44	-0.02
Martin ratio Return relative to average drawdown	8.51	9.39	-0.88
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

TAFTX vs. COSIX - Sharpe Ratio Comparison

The current TAFTX Sharpe Ratio is 2.60, which is higher than the COSIX Sharpe Ratio of 1.83. The chart below compares the historical Sharpe Ratios of TAFTX and COSIX, 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

	TAFTX	COSIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.60	1.83	+0.77
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.22	0.41	-0.20
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.53	0.86	-0.32
Sharpe Ratio (All Time) Calculated using the full available price history	1.28	1.01	+0.27

Drawdowns

TAFTX vs. COSIX - Drawdown Comparison

The maximum TAFTX drawdown since its inception was -18.83%, smaller than the maximum COSIX drawdown of -27.69%. Use the drawdown chart below to compare losses from any high point for TAFTX and COSIX.

Drawdown Indicators

	TAFTX	COSIX	Difference
Max Drawdown Largest peak-to-trough decline	-18.83%	-27.69%	+8.86%
Max Drawdown (1Y) Largest decline over 1 year	-3.05%	-2.21%	-0.84%
Max Drawdown (3Y) Largest decline over 3 years	-5.66%	-4.17%	-1.49%
Max Drawdown (5Y) Largest decline over 5 years	-14.82%	-16.88%	+2.06%
Max Drawdown (10Y) Largest decline over 10 years	-14.82%	-16.88%	+2.06%
Current Drawdown Current decline from peak	-0.46%	-0.02%	-0.44%
Average Drawdown Average peak-to-trough decline	-1.94%	-2.47%	+0.53%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.86%	0.57%	+0.29%

Volatility

TAFTX vs. COSIX - Volatility Comparison

American Funds Tax-Exempt Fund of California (TAFTX) has a higher volatility of 1.15% compared to Columbia Strategic Income Fund (COSIX) at 1.04%. This indicates that TAFTX's price experiences larger fluctuations and is considered to be riskier than COSIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	TAFTX	COSIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.15%	1.04%	+0.11%
Volatility (6M) Calculated over the trailing 6-month period	2.15%	2.21%	-0.06%
Volatility (1Y) Calculated over the trailing 1-year period	2.84%	2.95%	-0.11%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	4.05%	4.55%	-0.50%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	3.92%	4.17%	-0.25%

TAFTX vs. COSIX - Expense Ratio Comparison

TAFTX has a 0.57% expense ratio, which is lower than COSIX's 0.92% expense ratio.

Dividends

TAFTX vs. COSIX - Dividend Comparison

TAFTX's dividend yield for the trailing twelve months is around 3.04%, less than COSIX's 4.99% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
COSIX Columbia Strategic Income Fund	4.99%	4.94%	5.20%	5.03%	3.56%	3.86%	3.24%	3.71%	4.25%	3.51%	3.09%	4.20%
TAFTX American Funds Tax-Exempt Fund of California	3.04%	3.96%	2.64%	2.19%	1.82%	2.19%	2.65%	3.15%	2.93%	2.95%	3.13%	3.32%

Frequently Asked Questions

Can I hold both TAFTX and COSIX in my portfolio?

TAFTX and COSIX have a correlation of 0.56, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, TAFTX or COSIX?

TAFTX has higher volatility (1.15%) compared to COSIX (1.04%). In terms of maximum drawdown, TAFTX dropped -18.83% vs COSIX's -27.69%.

Which has better risk-adjusted returns?

TAFTX currently has the higher Sharpe Ratio (2.60 vs 1.83), meaning it's delivered slightly more return per unit of risk over the trailing 12 months. However, this ranking shifts over time - use the Risk/Return Score above for a more comprehensive view that combines Sharpe, Sortino, and other measures used by quantitative funds.