IFAFX vs. TIBAX

Last updated Jun 4, 2026

IFAFX (American Funds Income Fund of America Class F1) and TIBAX (Thornburg Investment Income Builder Fund) are both Global Allocation funds. Over the past 10 years, IFAFX returned 8.44%/yr vs 12.42%/yr for TIBAX. Their correlation of 0.86 suggests significant overlap in exposure. IFAFX charges 0.63%/yr vs 1.14%/yr for TIBAX.

Performance

IFAFX vs. TIBAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds Income Fund of America Class F1 (IFAFX) and Thornburg Investment Income Builder Fund (TIBAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, IFAFX achieves a 6.30% return, which is significantly lower than TIBAX's 17.92% return. Over the past 10 years, IFAFX has underperformed TIBAX with an annualized return of 8.44%, while TIBAX has yielded a comparatively higher 12.42% annualized return.

IFAFX

• 1D: 0.33%
• 1M: 0.96%
• YTD: 6.30%
• 6M: 7.35%
• 1Y: 15.67%
• 3Y*: 13.68%
• 5Y*: 7.70%
• 10Y*: 8.44%

TIBAX

• 1D: 0.63%
• 1M: 3.10%
• YTD: 17.92%
• 6M: 21.20%
• 1Y: 39.47%
• 3Y*: 26.52%
• 5Y*: 16.15%
• 10Y*: 12.42%

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

IFAFX vs. TIBAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
IFAFX American Funds Income Fund of America Class F1	6.30%	17.71%	10.76%	6.76%	-6.48%	17.28%	4.40%	18.41%	-5.33%	12.48%
TIBAX Thornburg Investment Income Builder Fund	17.92%	36.62%	13.23%	18.01%	-7.95%	20.08%	-0.67%	17.72%	-4.54%	14.83%

Correlation

The correlation between IFAFX and TIBAX is 0.72, 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	0.72
Correlation (3Y) Calculated over the trailing 3-year period	0.80
Correlation (5Y) Calculated over the trailing 5-year period	0.83
Correlation (10Y) Calculated over the trailing 10-year period	0.85
Correlation (All Time) Calculated using the full available price history since Dec 26, 2002	0.86

The correlation between IFAFX and TIBAX shifts across timeframes, from 0.72 (1 year) to 0.86 (all time), reflecting how their relationship changes across market environments.

Return for Risk

IFAFX vs. TIBAX — Risk / Return Rank

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

IFAFX

IFAFX Risk / Return Rank: 52
IFAFX Sharpe Ratio Rank: 56
IFAFX Sortino Ratio Rank: 55
IFAFX Omega Ratio Rank: 54
IFAFX Calmar Ratio Rank: 47
IFAFX Martin Ratio Rank: 47

TIBAX

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

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.

IFAFX vs. TIBAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds Income Fund of America Class F1 (IFAFX) and Thornburg Investment Income Builder Fund (TIBAX). 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.

	IFAFX	TIBAX	Difference
Sharpe ratio: Return per unit of total volatility	2.23	4.75	-2.52
Sortino ratio: Return per unit of downside risk	3.14	6.82	-3.68
Omega ratio: Gain probability vs. loss probability	1.41	1.96	-0.55
Calmar ratio: Return relative to maximum drawdown	2.61	7.36	-4.74
Martin ratio: Return relative to average drawdown	9.84	28.70	-18.87
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

IFAFX vs. TIBAX - Sharpe Ratio Comparison

The current IFAFX Sharpe Ratio is 2.23, which is lower than the TIBAX Sharpe Ratio of 4.75. The chart below compares the historical Sharpe Ratios of IFAFX and TIBAX, 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

	IFAFX	TIBAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.23	4.75	-2.52
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.82	1.46	-0.64
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.79	0.93	-0.13
Sharpe Ratio (All Time) Calculated using the full available price history	0.71	0.80	-0.09

Drawdowns

IFAFX vs. TIBAX - Drawdown Comparison

The maximum IFAFX drawdown since its inception was -41.90%, smaller than the maximum TIBAX drawdown of -49.12%. Use the drawdown chart below to compare losses from any high point for IFAFX and TIBAX.

Drawdown Indicators

	IFAFX	TIBAX	Difference
Max Drawdown Largest peak-to-trough decline	-41.90%	-49.12%	+7.22%
Max Drawdown (1Y) Largest decline over 1 year	-6.11%	-5.43%	-0.68%
Max Drawdown (3Y) Largest decline over 3 years	-8.63%	-9.20%	+0.57%
Max Drawdown (5Y) Largest decline over 5 years	-15.84%	-20.94%	+5.10%
Max Drawdown (10Y) Largest decline over 10 years	-26.13%	-34.85%	+8.72%
Current Drawdown Current decline from peak	-1.22%	0.00%	-1.22%
Average Drawdown Average peak-to-trough decline	-3.93%	-5.99%	+2.06%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.62%	1.39%	+0.23%

Volatility

IFAFX vs. TIBAX - Volatility Comparison

The current volatility for American Funds Income Fund of America Class F1 (IFAFX) is 2.07%, while Thornburg Investment Income Builder Fund (TIBAX) has a volatility of 3.12%. This indicates that IFAFX experiences smaller price fluctuations and is considered to be less risky than TIBAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	IFAFX	TIBAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.07%	3.12%	-1.05%
Volatility (6M) Calculated over the trailing 6-month period	5.62%	6.97%	-1.35%
Volatility (1Y) Calculated over the trailing 1-year period	7.17%	8.42%	-1.25%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	9.48%	11.12%	-1.64%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	10.68%	13.46%	-2.78%

IFAFX vs. TIBAX - Expense Ratio Comparison

IFAFX has a 0.63% expense ratio, which is lower than TIBAX's 1.14% expense ratio.

Dividends

IFAFX vs. TIBAX - Dividend Comparison

IFAFX's dividend yield for the trailing twelve months is around 9.38%, more than TIBAX's 4.85% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
IFAFX American Funds Income Fund of America Class F1	9.38%	9.91%	6.33%	2.90%	6.94%	6.61%	2.76%	4.95%	7.39%	4.20%	3.01%	5.02%
TIBAX Thornburg Investment Income Builder Fund	4.85%	5.64%	5.44%	4.67%	5.62%	5.10%	4.11%	4.23%	4.49%	4.22%	3.83%	4.31%

Frequently Asked Questions

Can I hold both IFAFX and TIBAX in my portfolio?

IFAFX and TIBAX have a correlation of 0.72, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, IFAFX or TIBAX?

TIBAX has higher volatility (3.12%) compared to IFAFX (2.07%). In terms of maximum drawdown, IFAFX dropped -41.90% vs TIBAX's -49.12%.

Which has better risk-adjusted returns?

TIBAX currently has the higher Sharpe Ratio (4.75 vs 2.23), 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.