TIBIX vs. CSTAX

Last updated Jun 4, 2026

TIBIX (Thornburg Investment Income Builder Fund Class I) and CSTAX (American Funds College 2027 Fund) are both Diversified Portfolio funds. Over the past 10 years, TIBIX returned 12.73%/yr vs 4.99%/yr for CSTAX. A 0.73 correlation means they provide meaningful diversification when combined. TIBIX charges 0.93%/yr vs 0.41%/yr for CSTAX.

Performance

TIBIX vs. CSTAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Thornburg Investment Income Builder Fund Class I (TIBIX) and American Funds College 2027 Fund (CSTAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, TIBIX achieves a 17.96% return, which is significantly higher than CSTAX's 1.47% return. Over the past 10 years, TIBIX has outperformed CSTAX with an annualized return of 12.73%, while CSTAX has yielded a comparatively lower 4.99% annualized return.

TIBIX

• 1D: 0.65%
• 1M: 3.13%
• YTD: 17.96%
• 6M: 21.37%
• 1Y: 39.83%
• 3Y*: 26.83%
• 5Y*: 16.44%
• 10Y*: 12.73%

CSTAX

• 1D: 0.08%
• 1M: 0.65%
• YTD: 1.47%
• 6M: 1.68%
• 1Y: 6.99%
• 3Y*: 6.87%
• 5Y*: 2.83%
• 10Y*: 4.99%

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

TIBIX vs. CSTAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
TIBIX Thornburg Investment Income Builder Fund Class I	17.96%	37.01%	13.48%	18.28%	-7.69%	20.36%	-0.40%	18.01%	-4.31%	15.23%
CSTAX American Funds College 2027 Fund	1.47%	9.00%	5.57%	6.57%	-9.87%	6.52%	7.66%	13.35%	-2.23%	11.77%

Correlation

The correlation between TIBIX and CSTAX is 0.49, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.49
Correlation (3Y) Calculated over the trailing 3-year period	0.54
Correlation (5Y) Calculated over the trailing 5-year period	0.56
Correlation (10Y) Calculated over the trailing 10-year period	0.67
Correlation (All Time) Calculated using the full available price history since Jan 3, 2013	0.73

Over the past year, the correlation between TIBIX and CSTAX has dropped to 0.49 - well below their long-term average of 0.73, suggesting their price drivers have been diverging.

Return for Risk

TIBIX vs. CSTAX — Risk / Return Rank

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

TIBIX

TIBIX Risk / Return Rank: 98
TIBIX Sharpe Ratio Rank: 99
TIBIX Sortino Ratio Rank: 98
TIBIX Omega Ratio Rank: 97
TIBIX Calmar Ratio Rank: 97
TIBIX Martin Ratio Rank: 98

CSTAX

CSTAX Risk / Return Rank: 60
CSTAX Sharpe Ratio Rank: 64
CSTAX Sortino Ratio Rank: 71
CSTAX Omega Ratio Rank: 70
CSTAX Calmar Ratio Rank: 47
CSTAX Martin Ratio Rank: 49

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.

TIBIX vs. CSTAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Thornburg Investment Income Builder Fund Class I (TIBIX) and American Funds College 2027 Fund (CSTAX). 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.

	TIBIX	CSTAX	Difference
Sharpe ratio: Return per unit of total volatility	4.77	2.34	+2.43
Sortino ratio: Return per unit of downside risk	6.85	3.52	+3.33
Omega ratio: Gain probability vs. loss probability	1.96	1.47	+0.49
Calmar ratio: Return relative to maximum drawdown	7.48	2.61	+4.87
Martin ratio: Return relative to average drawdown	29.20	10.06	+19.14
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

TIBIX vs. CSTAX - Sharpe Ratio Comparison

The current TIBIX Sharpe Ratio is 4.77, which is higher than the CSTAX Sharpe Ratio of 2.34. The chart below compares the historical Sharpe Ratios of TIBIX and CSTAX, 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

	TIBIX	CSTAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	4.77	2.34	+2.43
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	1.48	0.55	+0.93
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.95	0.86	+0.08
Sharpe Ratio (All Time) Calculated using the full available price history	0.77	0.88	-0.11

Drawdowns

TIBIX vs. CSTAX - Drawdown Comparison

The maximum TIBIX drawdown since its inception was -48.88%, which is greater than CSTAX's maximum drawdown of -14.52%. Use the drawdown chart below to compare losses from any high point for TIBIX and CSTAX.

Drawdown Indicators

	TIBIX	CSTAX	Difference
Max Drawdown Largest peak-to-trough decline	-48.88%	-14.52%	-34.36%
Max Drawdown (1Y) Largest decline over 1 year	-5.39%	-2.72%	-2.67%
Max Drawdown (3Y) Largest decline over 3 years	-9.23%	-4.89%	-4.34%
Max Drawdown (5Y) Largest decline over 5 years	-20.79%	-14.52%	-6.27%
Max Drawdown (10Y) Largest decline over 10 years	-34.85%	-14.52%	-20.33%
Current Drawdown Current decline from peak	0.00%	-0.40%	+0.40%
Average Drawdown Average peak-to-trough decline	-5.96%	-2.35%	-3.61%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.38%	0.70%	+0.68%

Volatility

TIBIX vs. CSTAX - Volatility Comparison

Thornburg Investment Income Builder Fund Class I (TIBIX) has a higher volatility of 3.12% compared to American Funds College 2027 Fund (CSTAX) at 1.11%. This indicates that TIBIX's price experiences larger fluctuations and is considered to be riskier than CSTAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	TIBIX	CSTAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.12%	1.11%	+2.01%
Volatility (6M) Calculated over the trailing 6-month period	6.99%	2.32%	+4.67%
Volatility (1Y) Calculated over the trailing 1-year period	8.46%	3.03%	+5.43%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	11.16%	5.16%	+6.00%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	13.50%	5.79%	+7.71%

TIBIX vs. CSTAX - Expense Ratio Comparison

TIBIX has a 0.93% expense ratio, which is higher than CSTAX's 0.41% expense ratio.

Dividends

TIBIX vs. CSTAX - Dividend Comparison

TIBIX's dividend yield for the trailing twelve months is around 5.03%, less than CSTAX's 5.19% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
CSTAX American Funds College 2027 Fund	5.19%	5.26%	3.78%	3.17%	3.40%	7.52%	5.72%	4.00%	4.78%	3.90%	4.34%	4.49%
TIBIX Thornburg Investment Income Builder Fund Class I	5.03%	5.83%	5.67%	4.89%	5.89%	5.33%	4.31%	4.46%	4.77%	4.52%	4.14%	4.66%

Frequently Asked Questions

Can I hold both TIBIX and CSTAX in my portfolio?

TIBIX and CSTAX have a correlation of 0.49, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, TIBIX or CSTAX?

TIBIX has higher volatility (3.12%) compared to CSTAX (1.11%). In terms of maximum drawdown, TIBIX dropped -48.88% vs CSTAX's -14.52%.

Which has better risk-adjusted returns?

TIBIX currently has the higher Sharpe Ratio (4.77 vs 2.34), 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.