TWHIX vs. FMDGX

Last updated Jun 3, 2026

TWHIX (American Century Heritage Fund) and FMDGX (Fidelity Mid Cap Growth Index Fund) are both Mid Cap Growth Equities funds. Over the past 5 years, TWHIX returned 6.21%/yr vs 7.05%/yr for FMDGX. With a 0.98 correlation, they move nearly in lockstep. TWHIX charges 1.00%/yr vs 0.05%/yr for FMDGX.

Performance

TWHIX vs. FMDGX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Century Heritage Fund (TWHIX) and Fidelity Mid Cap Growth Index Fund (FMDGX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, TWHIX achieves a 6.98% return, which is significantly higher than FMDGX's 5.10% return.

TWHIX

• 1D: 1.18%
• 1M: 6.72%
• YTD: 6.98%
• 6M: 5.65%
• 1Y: 8.70%
• 3Y*: 15.62%
• 5Y*: 6.21%
• 10Y*: 12.13%

FMDGX

• 1D: 0.66%
• 1M: 5.53%
• YTD: 5.10%
• 6M: 4.66%
• 1Y: 8.19%
• 3Y*: 16.50%
• 5Y*: 7.05%
• 10Y*: —

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

TWHIX vs. FMDGX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
TWHIX American Century Heritage Fund	6.98%	6.53%	24.66%	20.64%	-28.13%	11.52%	42.61%	3.18%
FMDGX Fidelity Mid Cap Growth Index Fund	5.10%	8.60%	22.03%	25.79%	-26.67%	12.67%	34.84%	4.63%

Correlation

The correlation between TWHIX and FMDGX is 0.98 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.98
Correlation (3Y) Calculated over the trailing 3-year period	0.97
Correlation (5Y) Calculated over the trailing 5-year period	0.98
Correlation (All Time) Calculated using the full available price history since Jul 18, 2019	0.98

The correlation between TWHIX and FMDGX has been stable across timeframes, ranging from 0.97 to 0.98 - a consistent structural relationship.

Return for Risk

TWHIX vs. FMDGX — Risk / Return Rank

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

TWHIX

TWHIX Risk / Return Rank: 6
TWHIX Sharpe Ratio Rank: 6
TWHIX Sortino Ratio Rank: 7
TWHIX Omega Ratio Rank: 6
TWHIX Calmar Ratio Rank: 6
TWHIX Martin Ratio Rank: 6

FMDGX

FMDGX Risk / Return Rank: 6
FMDGX Sharpe Ratio Rank: 6
FMDGX Sortino Ratio Rank: 6
FMDGX Omega Ratio Rank: 6
FMDGX Calmar Ratio Rank: 6
FMDGX Martin Ratio Rank: 6

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.

TWHIX vs. FMDGX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Century Heritage Fund (TWHIX) and Fidelity Mid Cap Growth Index Fund (FMDGX). 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.

	TWHIX	FMDGX	Difference
Sharpe ratio Return per unit of total volatility	0.54	0.52	+0.02
Sortino ratio Return per unit of downside risk	0.87	0.85	+0.03
Omega ratio Gain probability vs. loss probability	1.10	1.10	0.00
Calmar ratio Return relative to maximum drawdown	0.66	0.65	+0.01
Martin ratio Return relative to average drawdown	1.92	1.90	+0.02
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

TWHIX vs. FMDGX - Sharpe Ratio Comparison

The current TWHIX Sharpe Ratio is 0.54, which is comparable to the FMDGX Sharpe Ratio of 0.52. The chart below compares the historical Sharpe Ratios of TWHIX and FMDGX, 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

	TWHIX	FMDGX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.54	0.52	+0.02
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.27	0.32	-0.05
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.53	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.53	0.45	+0.08

Drawdowns

TWHIX vs. FMDGX - Drawdown Comparison

The maximum TWHIX drawdown since its inception was -56.98%, which is greater than FMDGX's maximum drawdown of -38.59%. Use the drawdown chart below to compare losses from any high point for TWHIX and FMDGX.

Drawdown Indicators

	TWHIX	FMDGX	Difference
Max Drawdown Largest peak-to-trough decline	-56.98%	-38.59%	-18.39%
Max Drawdown (1Y) Largest decline over 1 year	-15.82%	-14.75%	-1.07%
Max Drawdown (3Y) Largest decline over 3 years	-26.30%	-25.30%	-1.00%
Max Drawdown (5Y) Largest decline over 5 years	-40.34%	-38.59%	-1.75%
Max Drawdown (10Y) Largest decline over 10 years	-40.34%	—	—
Current Drawdown Current decline from peak	0.00%	-0.87%	+0.87%
Average Drawdown Average peak-to-trough decline	-12.25%	-11.21%	-1.04%
Ulcer Index Depth and duration of drawdowns from previous peaks	5.43%	5.05%	+0.38%

Volatility

TWHIX vs. FMDGX - Volatility Comparison

American Century Heritage Fund (TWHIX) has a higher volatility of 4.09% compared to Fidelity Mid Cap Growth Index Fund (FMDGX) at 3.51%. This indicates that TWHIX's price experiences larger fluctuations and is considered to be riskier than FMDGX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	TWHIX	FMDGX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.09%	3.51%	+0.58%
Volatility (6M) Calculated over the trailing 6-month period	13.71%	12.66%	+1.05%
Volatility (1Y) Calculated over the trailing 1-year period	17.39%	16.49%	+0.90%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	23.25%	22.37%	+0.88%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	22.82%	24.33%	-1.51%

TWHIX vs. FMDGX - Expense Ratio Comparison

TWHIX has a 1.00% expense ratio, which is higher than FMDGX's 0.05% expense ratio.

Dividends

TWHIX vs. FMDGX - Dividend Comparison

TWHIX's dividend yield for the trailing twelve months is around 20.69%, more than FMDGX's 1.76% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016
FMDGX Fidelity Mid Cap Growth Index Fund	1.76%	1.85%	0.47%	0.63%	0.81%	6.43%	0.36%	0.29%	0.00%	0.00%	0.00%
TWHIX American Century Heritage Fund	20.69%	22.14%	15.58%	0.78%	0.98%	12.00%	13.72%	11.32%	25.33%	9.38%	8.71%

Frequently Asked Questions

Can I hold both TWHIX and FMDGX in my portfolio?

With a correlation of 0.98, TWHIX and FMDGX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.

Which is riskier, TWHIX or FMDGX?

TWHIX has higher volatility (4.09%) compared to FMDGX (3.51%). In terms of maximum drawdown, TWHIX dropped -56.98% vs FMDGX's -38.59%.

Which has better risk-adjusted returns?

TWHIX currently has the higher Sharpe Ratio (0.54 vs 0.52), 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.