OTCAX vs. VIIIX

Last updated Jun 4, 2026

OTCAX (MFS Mid Cap Growth Fund) and VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) are both mutual funds - OTCAX is a Mid Cap Growth Equities fund managed by MFS, while VIIIX is a Large Cap Blend Equities fund managed by Vanguard. Over the past 10 years, OTCAX returned 12.24%/yr vs 15.74%/yr for VIIIX. Their correlation of 0.85 suggests significant overlap in exposure. OTCAX charges 1.00%/yr vs 0.02%/yr for VIIIX.

Performance

OTCAX vs. VIIIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Mid Cap Growth Fund (OTCAX) and Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, OTCAX achieves a 4.87% return, which is significantly lower than VIIIX's 11.70% return. Over the past 10 years, OTCAX has underperformed VIIIX with an annualized return of 12.24%, while VIIIX has yielded a comparatively higher 15.74% annualized return.

OTCAX

• 1D: 0.61%
• 1M: 3.80%
• YTD: 4.87%
• 6M: 3.45%
• 1Y: 4.29%
• 3Y*: 14.31%
• 5Y*: 5.78%
• 10Y*: 12.24%

VIIIX

• 1D: 0.13%
• 1M: 5.80%
• YTD: 11.70%
• 6M: 11.74%
• 1Y: 28.99%
• 3Y*: 23.17%
• 5Y*: 14.42%
• 10Y*: 15.74%

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

OTCAX vs. VIIIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
OTCAX MFS Mid Cap Growth Fund	4.87%	3.32%	23.47%	21.00%	-28.53%	13.66%	35.34%	37.43%	0.82%	25.95%
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares	11.70%	17.87%	26.29%	25.79%	-18.14%	28.69%	18.41%	31.48%	-4.41%	21.82%

Correlation

The correlation between OTCAX and VIIIX is 0.80, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.80
Correlation (3Y) Calculated over the trailing 3-year period	0.84
Correlation (5Y) Calculated over the trailing 5-year period	0.88
Correlation (10Y) Calculated over the trailing 10-year period	0.87
Correlation (All Time) Calculated using the full available price history since Jul 8, 1997	0.85

The correlation between OTCAX and VIIIX has been stable across timeframes, ranging from 0.80 to 0.88 - a consistent structural relationship.

Return for Risk

OTCAX vs. VIIIX — Risk / Return Rank

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

OTCAX

OTCAX Risk / Return Rank: 4
OTCAX Sharpe Ratio Rank: 4
OTCAX Sortino Ratio Rank: 4
OTCAX Omega Ratio Rank: 4
OTCAX Calmar Ratio Rank: 4
OTCAX Martin Ratio Rank: 4

VIIIX

VIIIX Risk / Return Rank: 73
VIIIX Sharpe Ratio Rank: 76
VIIIX Sortino Ratio Rank: 67
VIIIX Omega Ratio Rank: 67
VIIIX Calmar Ratio Rank: 74
VIIIX Martin Ratio Rank: 83

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.

OTCAX vs. VIIIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Mid Cap Growth Fund (OTCAX) and Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX). 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.

	OTCAX	VIIIX	Difference
Sharpe ratio Return per unit of total volatility	0.31	2.52	-2.21
Sortino ratio Return per unit of downside risk	0.55	3.42	-2.87
Omega ratio Gain probability vs. loss probability	1.06	1.46	-0.40
Calmar ratio Return relative to maximum drawdown	0.31	3.36	-3.05
Martin ratio Return relative to average drawdown	0.79	15.69	-14.90
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

OTCAX vs. VIIIX - Sharpe Ratio Comparison

The current OTCAX Sharpe Ratio is 0.31, which is lower than the VIIIX Sharpe Ratio of 2.52. The chart below compares the historical Sharpe Ratios of OTCAX and VIIIX, 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

	OTCAX	VIIIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.31	2.52	-2.21
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.29	0.86	-0.57
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.62	0.87	-0.26
Sharpe Ratio (All Time) Calculated using the full available price history	0.39	0.50	-0.11

Drawdowns

OTCAX vs. VIIIX - Drawdown Comparison

The maximum OTCAX drawdown since its inception was -74.39%, which is greater than VIIIX's maximum drawdown of -55.18%. Use the drawdown chart below to compare losses from any high point for OTCAX and VIIIX.

Drawdown Indicators

	OTCAX	VIIIX	Difference
Max Drawdown Largest peak-to-trough decline	-74.39%	-55.18%	-19.21%
Max Drawdown (1Y) Largest decline over 1 year	-16.46%	-8.90%	-7.56%
Max Drawdown (3Y) Largest decline over 3 years	-21.05%	-18.75%	-2.30%
Max Drawdown (5Y) Largest decline over 5 years	-36.85%	-24.50%	-12.35%
Max Drawdown (10Y) Largest decline over 10 years	-36.85%	-33.79%	-3.06%
Current Drawdown Current decline from peak	-3.02%	0.00%	-3.02%
Average Drawdown Average peak-to-trough decline	-23.13%	-10.02%	-13.11%
Ulcer Index Depth and duration of drawdowns from previous peaks	6.39%	1.90%	+4.49%

Volatility

OTCAX vs. VIIIX - Volatility Comparison

MFS Mid Cap Growth Fund (OTCAX) has a higher volatility of 4.19% compared to Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) at 2.83%. This indicates that OTCAX's price experiences larger fluctuations and is considered to be riskier than VIIIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OTCAX	VIIIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.19%	2.83%	+1.36%
Volatility (6M) Calculated over the trailing 6-month period	13.34%	8.97%	+4.37%
Volatility (1Y) Calculated over the trailing 1-year period	16.53%	11.86%	+4.67%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	20.18%	16.89%	+3.29%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	19.96%	18.06%	+1.90%

OTCAX vs. VIIIX - Expense Ratio Comparison

OTCAX has a 1.00% expense ratio, which is higher than VIIIX's 0.02% expense ratio.

Dividends

OTCAX vs. VIIIX - Dividend Comparison

OTCAX's dividend yield for the trailing twelve months is around 15.98%, more than VIIIX's 2.41% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
OTCAX MFS Mid Cap Growth Fund	15.98%	16.76%	15.59%	0.00%	0.00%	3.64%	0.83%	0.86%	4.70%	8.80%	5.67%	2.84%
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares	2.41%	2.11%	3.66%	2.66%	3.39%	4.79%	3.07%	2.86%	2.45%	1.84%	2.38%	2.47%

Frequently Asked Questions

Can I hold both OTCAX and VIIIX in my portfolio?

OTCAX and VIIIX have a correlation of 0.80, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, OTCAX or VIIIX?

OTCAX has higher volatility (4.19%) compared to VIIIX (2.83%). In terms of maximum drawdown, OTCAX dropped -74.39% vs VIIIX's -55.18%.

Which has better risk-adjusted returns?

VIIIX currently has the higher Sharpe Ratio (2.52 vs 0.31), 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.