NSIDX vs. BOSOX

Last updated Jul 17, 2026

NSIDX (Northern Small Cap Index Fund) and BOSOX (Boston Trust Small Cap Fund) are both Small Cap Blend Equities funds. Over the past 10 years, NSIDX returned 10.75%/yr vs 10.57%/yr for BOSOX. Their correlation of 0.94 suggests significant overlap in exposure. NSIDX charges 0.10%/yr vs 1.00%/yr for BOSOX.

Performance

NSIDX vs. BOSOX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Northern Small Cap Index Fund (NSIDX) and Boston Trust Small Cap Fund (BOSOX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, NSIDX achieves a 20.62% return, which is significantly higher than BOSOX's 12.97% return. Both investments have delivered pretty close results over the past 10 years, with NSIDX having a 10.75% annualized return and BOSOX not far behind at 10.57%.

NSIDX

• 1D: 0.38%
• 1M: 1.30%
• 6M: 11.94%
• YTD: 20.62%
• 1Y: 35.28%
• 3Y*: 17.09%
• 5Y*: 7.91%
• 10Y*: 10.75%

BOSOX

• 1D: 0.32%
• 1M: 2.29%
• 6M: 6.30%
• YTD: 12.97%
• 1Y: 12.52%
• 3Y*: 8.36%
• 5Y*: 6.61%
• 10Y*: 10.57%

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

NSIDX vs. BOSOX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
NSIDX Northern Small Cap Index Fund	20.62%	12.88%	11.45%	16.87%	-20.63%	14.38%	19.59%	25.22%	-11.33%	14.62%
BOSOX Boston Trust Small Cap Fund	12.97%	-4.04%	12.52%	10.09%	-9.05%	28.10%	8.27%	38.35%	-6.01%	12.24%

Correlation

The correlation between NSIDX and BOSOX is 0.68, 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	0.68
Correlation (3Y) Calculated over the trailing 3-year period	0.83
Correlation (5Y) Calculated over the trailing 5-year period	0.87
Correlation (10Y) Calculated over the trailing 10-year period	0.90
Correlation (All Time) Calculated using the full available price history since Dec 19, 2005	0.94

Over the past year, the correlation between NSIDX and BOSOX has dropped to 0.68 - well below their long-term average of 0.94, suggesting their price drivers have been diverging.

Return for Risk

NSIDX vs. BOSOX — Risk / Return Rank

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

NSIDX

NSIDX Risk / Return Rank: 73
NSIDX Sharpe Ratio Rank: 68
NSIDX Sortino Ratio Rank: 69
NSIDX Omega Ratio Rank: 58
NSIDX Calmar Ratio Rank: 86
NSIDX Martin Ratio Rank: 83

BOSOX

BOSOX Risk / Return Rank: 19
BOSOX Sharpe Ratio Rank: 17
BOSOX Sortino Ratio Rank: 20
BOSOX Omega Ratio Rank: 17
BOSOX Calmar Ratio Rank: 20
BOSOX Martin Ratio Rank: 21

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.

NSIDX vs. BOSOX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Northern Small Cap Index Fund (NSIDX) and Boston Trust Small Cap Fund (BOSOX). 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.

Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.

	NSIDX	BOSOX	Difference
Sharpe ratio: Return per unit of total volatility	1.86	0.89	+0.97
Sortino ratio: Return per unit of downside risk	2.67	1.45	+1.22
Omega ratio: Gain probability vs. loss probability	1.32	1.16	+0.16
Calmar ratio: Return relative to maximum drawdown	3.39	1.24	+2.14
Martin ratio: Return relative to average drawdown	11.90	3.88	+8.02

NSIDX vs. BOSOX - Sharpe Ratio Comparison

The current NSIDX Sharpe Ratio is 1.86, which is higher than the BOSOX Sharpe Ratio of 0.89. The chart below compares the historical Sharpe Ratios of NSIDX and BOSOX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Drawdowns

NSIDX vs. BOSOX - Drawdown Comparison

The maximum NSIDX drawdown since its inception was -59.02%, which is greater than BOSOX's maximum drawdown of -51.32%. Use the drawdown chart below to compare losses from any high point for NSIDX and BOSOX.

Drawdown Indicators

	NSIDX	BOSOX	Difference
Max Drawdown Largest peak-to-trough decline	-59.02%	-51.32%	-7.70%
Max Drawdown (1Y) Largest decline over 1 year	-10.97%	-10.69%	-0.28%
Max Drawdown (3Y) Largest decline over 3 years	-27.71%	-22.36%	-5.35%
Max Drawdown (5Y) Largest decline over 5 years	-32.89%	-22.36%	-10.53%
Max Drawdown (10Y) Largest decline over 10 years	-42.09%	-36.79%	-5.30%
Current Drawdown Current decline from peak	-1.58%	-1.58%	0.00%
Average Drawdown Average peak-to-trough decline	-12.01%	-7.25%	-4.76%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.11%	3.42%	-0.31%

Volatility

NSIDX vs. BOSOX - Volatility Comparison

The current volatility for Northern Small Cap Index Fund (NSIDX) is 3.75%, while Boston Trust Small Cap Fund (BOSOX) has a volatility of 4.10%. This indicates that NSIDX experiences smaller price fluctuations and is considered to be less risky than BOSOX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	NSIDX	BOSOX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.75%	4.10%	-0.35%
Volatility (6M) Calculated over the trailing 6-month period	14.22%	10.33%	+3.89%
Volatility (1Y) Calculated over the trailing 1-year period	20.14%	15.11%	+5.03%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	24.25%	17.84%	+6.41%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.22%	19.50%	+4.72%

NSIDX vs. BOSOX - Expense Ratio Comparison

NSIDX has a 0.10% expense ratio, which is lower than BOSOX's 1.00% expense ratio.

Dividends

NSIDX vs. BOSOX - Dividend Comparison

NSIDX's dividend yield for the trailing twelve months is around 1.30%, less than BOSOX's 3.90% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
BOSOX Boston Trust Small Cap Fund	3.90%	4.41%	6.52%	0.78%	5.09%	8.93%	2.56%	12.46%	16.19%	9.13%	3.14%	18.92%
NSIDX Northern Small Cap Index Fund	1.30%	1.57%	6.72%	2.01%	6.38%	12.15%	3.52%	1.78%	12.16%	6.55%	4.06%	6.68%

Frequently Asked Questions

Can I hold both NSIDX and BOSOX in my portfolio?

NSIDX and BOSOX have a correlation of 0.68, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, NSIDX or BOSOX?

BOSOX has higher volatility (4.10%) compared to NSIDX (3.75%). In terms of maximum drawdown, NSIDX dropped -59.02% vs BOSOX's -51.32%.

Which has better risk-adjusted returns?

NSIDX currently has the higher Sharpe Ratio (1.86 vs 0.89), 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.