OTCKX vs. VIMSX

Last updated Jun 4, 2026

OTCKX (MFS Mid Cap Growth Fund Class R6) and VIMSX (Vanguard Mid Cap Index Fund) are both mutual funds - OTCKX is a Mid Cap Growth Equities fund actively managed by MFS, while VIMSX is a Mid Cap Blend Equities fund managed by Vanguard. Over the past 10 years, OTCKX returned 12.88%/yr vs 11.40%/yr for VIMSX. Their correlation of 0.90 suggests significant overlap in exposure. OTCKX charges 0.65%/yr vs 0.17%/yr for VIMSX.

Performance

OTCKX vs. VIMSX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Mid Cap Growth Fund Class R6 (OTCKX) and Vanguard Mid Cap Index Fund (VIMSX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, OTCKX achieves a 4.99% return, which is significantly lower than VIMSX's 10.48% return. Over the past 10 years, OTCKX has outperformed VIMSX with an annualized return of 12.88%, while VIMSX has yielded a comparatively lower 11.40% annualized return.

OTCKX

• 1D: 0.57%
• 1M: 3.79%
• YTD: 4.99%
• 6M: 3.62%
• 1Y: 4.66%
• 3Y*: 15.51%
• 5Y*: 6.61%
• 10Y*: 12.88%

VIMSX

• 1D: 0.90%
• 1M: 3.66%
• YTD: 10.48%
• 6M: 10.13%
• 1Y: 18.59%
• 3Y*: 16.52%
• 5Y*: 7.88%
• 10Y*: 11.40%

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

OTCKX vs. VIMSX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
OTCKX MFS Mid Cap Growth Fund Class R6	4.99%	3.75%	26.48%	21.50%	-28.29%	14.09%	35.81%	37.93%	1.19%	26.35%
VIMSX Vanguard Mid Cap Index Fund	10.48%	11.08%	14.52%	16.40%	-18.80%	24.36%	18.04%	30.85%	-9.35%	19.12%

Correlation

The correlation between OTCKX and VIMSX is 0.84, 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	0.84
Correlation (3Y) Calculated over the trailing 3-year period	0.86
Correlation (5Y) Calculated over the trailing 5-year period	0.90
Correlation (10Y) Calculated over the trailing 10-year period	0.89
Correlation (All Time) Calculated using the full available price history since Jan 3, 2014	0.90

The correlation between OTCKX and VIMSX has been stable across timeframes, ranging from 0.84 to 0.90 - a consistent structural relationship.

Return for Risk

OTCKX vs. VIMSX — Risk / Return Rank

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

OTCKX

OTCKX Risk / Return Rank: 5
OTCKX Sharpe Ratio Rank: 5
OTCKX Sortino Ratio Rank: 5
OTCKX Omega Ratio Rank: 4
OTCKX Calmar Ratio Rank: 5
OTCKX Martin Ratio Rank: 5

VIMSX

VIMSX Risk / Return Rank: 35
VIMSX Sharpe Ratio Rank: 31
VIMSX Sortino Ratio Rank: 30
VIMSX Omega Ratio Rank: 29
VIMSX Calmar Ratio Rank: 41
VIMSX Martin Ratio Rank: 44

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.

OTCKX vs. VIMSX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Mid Cap Growth Fund Class R6 (OTCKX) and Vanguard Mid Cap Index Fund (VIMSX). 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.

	OTCKX	VIMSX	Difference
Sharpe ratio Return per unit of total volatility	0.33	1.60	-1.27
Sortino ratio Return per unit of downside risk	0.58	2.29	-1.71
Omega ratio Gain probability vs. loss probability	1.07	1.28	-0.21
Calmar ratio Return relative to maximum drawdown	0.33	2.42	-2.09
Martin ratio Return relative to average drawdown	0.86	9.19	-8.33
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

OTCKX vs. VIMSX - Sharpe Ratio Comparison

The current OTCKX Sharpe Ratio is 0.33, which is lower than the VIMSX Sharpe Ratio of 1.60. The chart below compares the historical Sharpe Ratios of OTCKX and VIMSX, 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

	OTCKX	VIMSX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.33	1.60	-1.27
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.33	0.45	-0.12
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.64	0.60	+0.04
Sharpe Ratio (All Time) Calculated using the full available price history	0.60	0.48	+0.13

Drawdowns

OTCKX vs. VIMSX - Drawdown Comparison

The maximum OTCKX drawdown since its inception was -36.64%, smaller than the maximum VIMSX drawdown of -58.96%. Use the drawdown chart below to compare losses from any high point for OTCKX and VIMSX.

Drawdown Indicators

	OTCKX	VIMSX	Difference
Max Drawdown Largest peak-to-trough decline	-36.64%	-58.96%	+22.32%
Max Drawdown (1Y) Largest decline over 1 year	-16.31%	-8.14%	-8.17%
Max Drawdown (3Y) Largest decline over 3 years	-20.99%	-19.31%	-1.68%
Max Drawdown (5Y) Largest decline over 5 years	-36.64%	-27.63%	-9.01%
Max Drawdown (10Y) Largest decline over 10 years	-36.64%	-39.29%	+2.65%
Current Drawdown Current decline from peak	-2.80%	0.00%	-2.80%
Average Drawdown Average peak-to-trough decline	-7.36%	-8.07%	+0.71%
Ulcer Index Depth and duration of drawdowns from previous peaks	6.29%	2.14%	+4.15%

Volatility

OTCKX vs. VIMSX - Volatility Comparison

MFS Mid Cap Growth Fund Class R6 (OTCKX) has a higher volatility of 4.21% compared to Vanguard Mid Cap Index Fund (VIMSX) at 2.97%. This indicates that OTCKX's price experiences larger fluctuations and is considered to be riskier than VIMSX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OTCKX	VIMSX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.21%	2.97%	+1.24%
Volatility (6M) Calculated over the trailing 6-month period	13.34%	9.28%	+4.06%
Volatility (1Y) Calculated over the trailing 1-year period	16.54%	12.30%	+4.24%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	20.37%	17.64%	+2.73%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.07%	18.93%	+1.14%

OTCKX vs. VIMSX - Expense Ratio Comparison

OTCKX has a 0.65% expense ratio, which is higher than VIMSX's 0.17% expense ratio.

Dividends

OTCKX vs. VIMSX - Dividend Comparison

OTCKX's dividend yield for the trailing twelve months is around 14.18%, more than VIMSX's 1.23% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
OTCKX MFS Mid Cap Growth Fund Class R6	14.18%	14.88%	16.85%	0.00%	0.00%	3.35%	0.77%	0.81%	4.40%	8.28%	5.38%	2.72%
VIMSX Vanguard Mid Cap Index Fund	1.23%	1.03%	1.37%	1.39%	1.46%	1.00%	1.34%	1.37%	1.68%	1.24%	1.34%	1.33%

Frequently Asked Questions

Can I hold both OTCKX and VIMSX in my portfolio?

OTCKX and VIMSX have a correlation of 0.84, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, OTCKX or VIMSX?

OTCKX has higher volatility (4.21%) compared to VIMSX (2.97%). In terms of maximum drawdown, OTCKX dropped -36.64% vs VIMSX's -58.96%.

Which has better risk-adjusted returns?

VIMSX currently has the higher Sharpe Ratio (1.60 vs 0.33), 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.