MAMEX vs. BIGTX

Last updated Jun 4, 2026

MAMEX (Mutual of America Mid-Cap Equity Index Fund) and BIGTX (The Texas Fund) are both Mid Cap Blend Equities funds. Over the past 5 years, MAMEX returned 7.22%/yr vs 9.45%/yr for BIGTX. A 0.78 correlation means they provide meaningful diversification when combined. MAMEX charges 0.16%/yr vs 1.67%/yr for BIGTX.

Performance

MAMEX vs. BIGTX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Mutual of America Mid-Cap Equity Index Fund (MAMEX) and The Texas Fund (BIGTX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MAMEX achieves a 14.08% return, which is significantly lower than BIGTX's 26.40% return.

MAMEX

• 1D: 0.88%
• 1M: 3.94%
• YTD: 14.08%
• 6M: 14.46%
• 1Y: 25.52%
• 3Y*: 15.21%
• 5Y*: 7.22%
• 10Y*: —

BIGTX

• 1D: 1.52%
• 1M: 7.30%
• YTD: 26.40%
• 6M: 23.78%
• 1Y: 36.15%
• 3Y*: 20.96%
• 5Y*: 9.45%
• 10Y*: 10.78%

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

MAMEX vs. BIGTX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020
MAMEX Mutual of America Mid-Cap Equity Index Fund	14.08%	7.40%	13.08%	13.99%	-13.59%	23.35%	925.33%
BIGTX The Texas Fund	26.40%	5.98%	15.76%	11.32%	-6.93%	23.90%	12.78%

Correlation

The correlation between MAMEX and BIGTX is 0.70, 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	0.70
Correlation (3Y) Calculated over the trailing 3-year period	0.82
Correlation (5Y) Calculated over the trailing 5-year period	0.77
Correlation (All Time) Calculated using the full available price history since Jan 3, 2020	0.78

The correlation between MAMEX and BIGTX shifts across timeframes, from 0.70 (1 year) to 0.82 (3 years), reflecting how their relationship changes across market environments.

Return for Risk

MAMEX vs. BIGTX — Risk / Return Rank

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

MAMEX

MAMEX Risk / Return Rank: 54
MAMEX Sharpe Ratio Rank: 42
MAMEX Sortino Ratio Rank: 45
MAMEX Omega Ratio Rank: 40
MAMEX Calmar Ratio Rank: 76
MAMEX Martin Ratio Rank: 68

BIGTX

BIGTX Risk / Return Rank: 82
BIGTX Sharpe Ratio Rank: 85
BIGTX Sortino Ratio Rank: 77
BIGTX Omega Ratio Rank: 67
BIGTX Calmar Ratio Rank: 90
BIGTX Martin Ratio Rank: 88

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.

MAMEX vs. BIGTX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Mutual of America Mid-Cap Equity Index Fund (MAMEX) and The Texas Fund (BIGTX). 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.

	MAMEX	BIGTX	Difference
Sharpe ratio: Return per unit of total volatility	1.90	2.74	-0.84
Sortino ratio: Return per unit of downside risk	2.82	3.68	-0.86
Omega ratio: Gain probability vs. loss probability	1.34	1.46	-0.12
Calmar ratio: Return relative to maximum drawdown	3.45	4.71	-1.26
Martin ratio: Return relative to average drawdown	13.17	17.23	-4.06
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

MAMEX vs. BIGTX - Sharpe Ratio Comparison

The current MAMEX Sharpe Ratio is 1.90, which is lower than the BIGTX Sharpe Ratio of 2.74. The chart below compares the historical Sharpe Ratios of MAMEX and BIGTX, 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

	MAMEX	BIGTX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.90	2.74	-0.84
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.37	0.07	+0.29
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.12	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.17	0.09	+0.08

Drawdowns

MAMEX vs. BIGTX - Drawdown Comparison

The maximum MAMEX drawdown since its inception was -42.17%, smaller than the maximum BIGTX drawdown of -77.89%. Use the drawdown chart below to compare losses from any high point for MAMEX and BIGTX.

Drawdown Indicators

	MAMEX	BIGTX	Difference
Max Drawdown Largest peak-to-trough decline	-42.17%	-77.89%	+35.72%
Max Drawdown (1Y) Largest decline over 1 year	-8.84%	-8.07%	-0.77%
Max Drawdown (3Y) Largest decline over 3 years	-24.11%	-77.89%	+53.78%
Max Drawdown (5Y) Largest decline over 5 years	-24.39%	-77.89%	+53.50%
Max Drawdown (10Y) Largest decline over 10 years	—	-77.89%	—
Current Drawdown Current decline from peak	0.00%	-64.86%	+64.86%
Average Drawdown Average peak-to-trough decline	-7.50%	-17.16%	+9.66%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.28%	2.20%	+0.08%

Volatility

MAMEX vs. BIGTX - Volatility Comparison

Mutual of America Mid-Cap Equity Index Fund (MAMEX) has a higher volatility of 4.43% compared to The Texas Fund (BIGTX) at 4.04%. This indicates that MAMEX's price experiences larger fluctuations and is considered to be riskier than BIGTX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MAMEX	BIGTX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.43%	4.04%	+0.39%
Volatility (6M) Calculated over the trailing 6-month period	12.23%	10.19%	+2.04%
Volatility (1Y) Calculated over the trailing 1-year period	16.08%	13.90%	+2.18%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.01%	126.63%	-104.62%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	383.36%	90.64%	+292.72%

MAMEX vs. BIGTX - Expense Ratio Comparison

MAMEX has a 0.16% expense ratio, which is lower than BIGTX's 1.67% expense ratio.

Dividends

MAMEX vs. BIGTX - Dividend Comparison

MAMEX's dividend yield for the trailing twelve months is around 10.39%, more than BIGTX's 5.84% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018
BIGTX The Texas Fund	5.84%	7.38%	3.52%	2.51%	3.06%	5.27%	0.07%	0.08%	2.27%
MAMEX Mutual of America Mid-Cap Equity Index Fund	10.39%	11.85%	9.07%	7.67%	14.01%	12.96%	0.00%	0.00%	0.00%

Frequently Asked Questions

Can I hold both MAMEX and BIGTX in my portfolio?

MAMEX and BIGTX have a correlation of 0.70, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MAMEX or BIGTX?

MAMEX has higher volatility (4.43%) compared to BIGTX (4.04%). In terms of maximum drawdown, MAMEX dropped -42.17% vs BIGTX's -77.89%.

Which has better risk-adjusted returns?

BIGTX currently has the higher Sharpe Ratio (2.74 vs 1.90), 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.