NMPAX vs. BTMFX

Last updated Jun 4, 2026

NMPAX (Columbia Mid Cap Index Fund) and BTMFX (Boston Trust Midcap Fund) are both Mid Cap Blend Equities funds. Over the past 10 years, NMPAX returned 10.61%/yr vs 10.08%/yr for BTMFX. Their correlation of 0.94 suggests significant overlap in exposure. NMPAX charges 0.20%/yr vs 1.00%/yr for BTMFX.

Performance

NMPAX vs. BTMFX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Columbia Mid Cap Index Fund (NMPAX) and Boston Trust Midcap Fund (BTMFX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, NMPAX achieves a 14.09% return, which is significantly higher than BTMFX's 1.92% return. Both investments have delivered pretty close results over the past 10 years, with NMPAX having a 10.61% annualized return and BTMFX not far behind at 10.08%.

NMPAX

• 1D: 0.87%
• 1M: 3.92%
• YTD: 14.09%
• 6M: 14.29%
• 1Y: 25.37%
• 3Y*: 15.95%
• 5Y*: 8.16%
• 10Y*: 10.61%

BTMFX

• 1D: 0.26%
• 1M: 1.74%
• YTD: 1.92%
• 6M: 1.46%
• 1Y: 5.64%
• 3Y*: 9.29%
• 5Y*: 5.63%
• 10Y*: 10.08%

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

NMPAX vs. BTMFX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
NMPAX Columbia Mid Cap Index Fund	14.09%	7.23%	13.67%	16.32%	-13.27%	24.66%	8.71%	25.99%	-11.44%	15.84%
BTMFX Boston Trust Midcap Fund	1.92%	4.29%	10.27%	13.06%	-10.91%	24.77%	9.72%	33.00%	-3.36%	20.01%

Correlation

The correlation between NMPAX and BTMFX 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	0.89
Correlation (5Y) Calculated over the trailing 5-year period	0.91
Correlation (10Y) Calculated over the trailing 10-year period	0.92
Correlation (All Time) Calculated using the full available price history since Oct 1, 2007	0.94

The correlation between NMPAX and BTMFX has been stable across timeframes, ranging from 0.84 to 0.94 - a consistent structural relationship.

Return for Risk

NMPAX vs. BTMFX — Risk / Return Rank

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

NMPAX

NMPAX Risk / Return Rank: 45
NMPAX Sharpe Ratio Rank: 36
NMPAX Sortino Ratio Rank: 36
NMPAX Omega Ratio Rank: 34
NMPAX Calmar Ratio Rank: 63
NMPAX Martin Ratio Rank: 56

BTMFX

BTMFX Risk / Return Rank: 7
BTMFX Sharpe Ratio Rank: 7
BTMFX Sortino Ratio Rank: 7
BTMFX Omega Ratio Rank: 6
BTMFX Calmar Ratio Rank: 8
BTMFX Martin Ratio Rank: 8

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.

NMPAX vs. BTMFX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Columbia Mid Cap Index Fund (NMPAX) and Boston Trust Midcap Fund (BTMFX). 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.

	NMPAX	BTMFX	Difference
Sharpe ratio: Return per unit of total volatility	1.74	0.56	+1.18
Sortino ratio: Return per unit of downside risk	2.53	0.91	+1.61
Omega ratio: Gain probability vs. loss probability	1.31	1.10	+0.20
Calmar ratio: Return relative to maximum drawdown	3.06	0.84	+2.21
Martin ratio: Return relative to average drawdown	11.17	2.35	+8.82
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

NMPAX vs. BTMFX - Sharpe Ratio Comparison

The current NMPAX Sharpe Ratio is 1.74, which is higher than the BTMFX Sharpe Ratio of 0.56. The chart below compares the historical Sharpe Ratios of NMPAX and BTMFX, 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

	NMPAX	BTMFX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.74	0.56	+1.18
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.42	0.36	+0.06
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.50	0.58	-0.08
Sharpe Ratio (All Time) Calculated using the full available price history	0.44	0.48	-0.04

Drawdowns

NMPAX vs. BTMFX - Drawdown Comparison

The maximum NMPAX drawdown since its inception was -54.31%, which is greater than BTMFX's maximum drawdown of -49.26%. Use the drawdown chart below to compare losses from any high point for NMPAX and BTMFX.

Drawdown Indicators

	NMPAX	BTMFX	Difference
Max Drawdown Largest peak-to-trough decline	-54.31%	-49.26%	-5.05%
Max Drawdown (1Y) Largest decline over 1 year	-8.84%	-7.79%	-1.05%
Max Drawdown (3Y) Largest decline over 3 years	-24.03%	-17.77%	-6.26%
Max Drawdown (5Y) Largest decline over 5 years	-24.03%	-20.79%	-3.24%
Max Drawdown (10Y) Largest decline over 10 years	-42.09%	-37.14%	-4.95%
Current Drawdown Current decline from peak	0.00%	-2.54%	+2.54%
Average Drawdown Average peak-to-trough decline	-7.73%	-6.16%	-1.57%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.41%	2.80%	-0.39%

Volatility

NMPAX vs. BTMFX - Volatility Comparison

Columbia Mid Cap Index Fund (NMPAX) has a higher volatility of 4.45% compared to Boston Trust Midcap Fund (BTMFX) at 2.88%. This indicates that NMPAX's price experiences larger fluctuations and is considered to be riskier than BTMFX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	NMPAX	BTMFX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.45%	2.88%	+1.57%
Volatility (6M) Calculated over the trailing 6-month period	11.37%	7.99%	+3.38%
Volatility (1Y) Calculated over the trailing 1-year period	15.51%	11.80%	+3.71%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	19.71%	15.75%	+3.96%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	21.12%	17.44%	+3.68%

NMPAX vs. BTMFX - Expense Ratio Comparison

NMPAX has a 0.20% expense ratio, which is lower than BTMFX's 1.00% expense ratio.

Dividends

NMPAX vs. BTMFX - Dividend Comparison

NMPAX's dividend yield for the trailing twelve months is around 8.18%, less than BTMFX's 10.66% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
BTMFX Boston Trust Midcap Fund	10.66%	10.86%	4.23%	4.41%	4.71%	4.91%	1.98%	6.95%	5.96%	6.61%	7.03%	6.60%
NMPAX Columbia Mid Cap Index Fund	8.18%	9.34%	11.35%	7.97%	11.65%	18.03%	5.96%	5.70%	10.06%	7.66%	7.97%	10.12%

Frequently Asked Questions

Can I hold both NMPAX and BTMFX in my portfolio?

NMPAX and BTMFX 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, NMPAX or BTMFX?

NMPAX has higher volatility (4.45%) compared to BTMFX (2.88%). In terms of maximum drawdown, NMPAX dropped -54.31% vs BTMFX's -49.26%.

Which has better risk-adjusted returns?

NMPAX currently has the higher Sharpe Ratio (1.74 vs 0.56), 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.