GCBLX vs. CSTAX

Last updated Jun 5, 2026

GCBLX (Green Century Balanced Fund) and CSTAX (American Funds College 2027 Fund) are both Diversified Portfolio funds. Over the past 10 years, GCBLX returned 8.35%/yr vs 4.97%/yr for CSTAX. Their correlation of 0.81 suggests significant overlap in exposure. GCBLX charges 1.46%/yr vs 0.41%/yr for CSTAX.

Performance

GCBLX vs. CSTAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Green Century Balanced Fund (GCBLX) 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, GCBLX achieves a 7.01% return, which is significantly higher than CSTAX's 1.30% return. Over the past 10 years, GCBLX has outperformed CSTAX with an annualized return of 8.35%, while CSTAX has yielded a comparatively lower 4.97% annualized return.

GCBLX

• 1D: -0.50%
• 1M: 3.19%
• YTD: 7.01%
• 6M: 6.79%
• 1Y: 13.73%
• 3Y*: 10.64%
• 5Y*: 5.36%
• 10Y*: 8.35%

CSTAX

• 1D: -0.16%
• 1M: 0.40%
• YTD: 1.30%
• 6M: 1.67%
• 1Y: 6.47%
• 3Y*: 6.81%
• 5Y*: 2.74%
• 10Y*: 4.97%

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

GCBLX vs. CSTAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
GCBLX Green Century Balanced Fund	7.01%	8.58%	9.67%	11.78%	-16.19%	16.43%	15.97%	20.90%	-2.14%	12.78%
CSTAX American Funds College 2027 Fund	1.30%	9.00%	5.57%	6.57%	-9.87%	6.52%	7.66%	13.35%	-2.23%	11.77%

Correlation

The correlation between GCBLX and CSTAX is 0.67, 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	0.67
Correlation (3Y) Calculated over the trailing 3-year period	0.70
Correlation (5Y) Calculated over the trailing 5-year period	0.71
Correlation (10Y) Calculated over the trailing 10-year period	0.78
Correlation (All Time) Calculated using the full available price history since Jan 3, 2013	0.81

The correlation between GCBLX and CSTAX shifts across timeframes, from 0.67 (1 year) to 0.81 (all time), reflecting how their relationship changes across market environments.

Return for Risk

GCBLX vs. CSTAX — Risk / Return Rank

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

GCBLX

GCBLX Risk / Return Rank: 39
GCBLX Sharpe Ratio Rank: 39
GCBLX Sortino Ratio Rank: 40
GCBLX Omega Ratio Rank: 39
GCBLX Calmar Ratio Rank: 32
GCBLX Martin Ratio Rank: 44

CSTAX

CSTAX Risk / Return Rank: 56
CSTAX Sharpe Ratio Rank: 59
CSTAX Sortino Ratio Rank: 66
CSTAX Omega Ratio Rank: 65
CSTAX Calmar Ratio Rank: 44
CSTAX Martin Ratio Rank: 47

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.

GCBLX vs. CSTAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Green Century Balanced Fund (GCBLX) 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.

	GCBLX	CSTAX	Difference
Sharpe ratio: Return per unit of total volatility	1.76	2.25	-0.49
Sortino ratio: Return per unit of downside risk	2.60	3.38	-0.78
Omega ratio: Gain probability vs. loss probability	1.32	1.45	-0.12
Calmar ratio: Return relative to maximum drawdown	2.06	2.52	-0.45
Martin ratio: Return relative to average drawdown	9.09	9.68	-0.59
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

GCBLX vs. CSTAX - Sharpe Ratio Comparison

The current GCBLX Sharpe Ratio is 1.76, which is comparable to the CSTAX Sharpe Ratio of 2.25. The chart below compares the historical Sharpe Ratios of GCBLX 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

	GCBLX	CSTAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.76	2.25	-0.49
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.47	0.53	-0.06
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.72	0.86	-0.14
Sharpe Ratio (All Time) Calculated using the full available price history	0.48	0.87	-0.40

Drawdowns

GCBLX vs. CSTAX - Drawdown Comparison

The maximum GCBLX drawdown since its inception was -64.30%, which is greater than CSTAX's maximum drawdown of -14.52%. Use the drawdown chart below to compare losses from any high point for GCBLX and CSTAX.

Drawdown Indicators

	GCBLX	CSTAX	Difference
Max Drawdown Largest peak-to-trough decline	-64.30%	-14.52%	-49.78%
Max Drawdown (1Y) Largest decline over 1 year	-6.81%	-2.72%	-4.09%
Max Drawdown (3Y) Largest decline over 3 years	-13.03%	-4.89%	-8.14%
Max Drawdown (5Y) Largest decline over 5 years	-21.88%	-14.52%	-7.36%
Max Drawdown (10Y) Largest decline over 10 years	-22.38%	-14.52%	-7.86%
Current Drawdown Current decline from peak	-0.50%	-0.56%	+0.06%
Average Drawdown Average peak-to-trough decline	-14.56%	-2.35%	-12.21%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.54%	0.71%	+0.83%

Volatility

GCBLX vs. CSTAX - Volatility Comparison

Green Century Balanced Fund (GCBLX) has a higher volatility of 2.32% compared to American Funds College 2027 Fund (CSTAX) at 1.10%. This indicates that GCBLX'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

	GCBLX	CSTAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.32%	1.10%	+1.22%
Volatility (6M) Calculated over the trailing 6-month period	6.30%	2.31%	+3.99%
Volatility (1Y) Calculated over the trailing 1-year period	7.98%	3.04%	+4.94%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	11.35%	5.16%	+6.19%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	11.59%	5.79%	+5.80%

GCBLX vs. CSTAX - Expense Ratio Comparison

GCBLX has a 1.46% expense ratio, which is higher than CSTAX's 0.41% expense ratio.

Dividends

GCBLX vs. CSTAX - Dividend Comparison

GCBLX's dividend yield for the trailing twelve months is around 4.54%, less than CSTAX's 5.20% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
CSTAX American Funds College 2027 Fund	5.20%	5.26%	3.78%	3.17%	3.40%	7.52%	5.72%	4.00%	4.78%	3.90%	4.34%	4.49%
GCBLX Green Century Balanced Fund	4.54%	4.86%	7.00%	3.02%	1.88%	3.99%	3.61%	1.92%	2.36%	1.29%	2.14%	2.97%

Frequently Asked Questions

Can I hold both GCBLX and CSTAX in my portfolio?

GCBLX and CSTAX have a correlation of 0.67, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, GCBLX or CSTAX?

GCBLX has higher volatility (2.32%) compared to CSTAX (1.10%). In terms of maximum drawdown, GCBLX dropped -64.30% vs CSTAX's -14.52%.

Which has better risk-adjusted returns?

CSTAX currently has the higher Sharpe Ratio (2.25 vs 1.76), 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.