NSIDX vs. PEXMX

Last updated Jun 24, 2026

NSIDX (Northern Small Cap Index Fund) and PEXMX (T. Rowe Price Extended Equity Market Index Fund) are both mutual funds - NSIDX is a Small Cap Blend Equities fund managed by Northern Funds, while PEXMX is a Mid Cap Growth Equities fund managed by T. Rowe Price. Over the past 10 years, NSIDX returned 11.61%/yr vs 12.66%/yr for PEXMX. With a 0.96 correlation, they move nearly in lockstep. NSIDX charges 0.10%/yr vs 0.23%/yr for PEXMX.

Performance

NSIDX vs. PEXMX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Northern Small Cap Index Fund (NSIDX) and T. Rowe Price Extended Equity Market Index Fund (PEXMX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, NSIDX achieves a 21.65% return, which is significantly higher than PEXMX's 15.23% return. Over the past 10 years, NSIDX has underperformed PEXMX with an annualized return of 11.61%, while PEXMX has yielded a comparatively higher 12.66% annualized return.

NSIDX

• 1D: 0.80%
• 1M: 4.79%
• YTD: 21.65%
• 6M: 18.89%
• 1Y: 42.65%
• 3Y*: 19.76%
• 5Y*: 6.76%
• 10Y*: 11.61%

PEXMX

• 1D: -0.10%
• 1M: 4.28%
• YTD: 15.23%
• 6M: 12.88%
• 1Y: 28.97%
• 3Y*: 20.05%
• 5Y*: 6.31%
• 10Y*: 12.66%

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

NSIDX vs. PEXMX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
NSIDX Northern Small Cap Index Fund	21.65%	12.88%	11.45%	16.87%	-20.63%	14.38%	19.59%	25.22%	-11.33%	14.62%
PEXMX T. Rowe Price Extended Equity Market Index Fund	15.23%	11.17%	16.72%	25.32%	-26.15%	12.09%	30.80%	32.57%	-9.61%	16.63%

Correlation

The correlation between NSIDX and PEXMX is 0.82, 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	0.82
Correlation (3Y) Calculated over the trailing 3-year period	0.90
Correlation (5Y) Calculated over the trailing 5-year period	0.93
Correlation (10Y) Calculated over the trailing 10-year period	0.94
Correlation (All Time) Calculated using the full available price history since Sep 3, 1999	0.96

The correlation between NSIDX and PEXMX shifts across timeframes, from 0.82 (1 year) to 0.96 (all time), reflecting how their relationship changes across market environments.

Return for Risk

NSIDX vs. PEXMX — Risk / Return Rank

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

NSIDX

NSIDX Risk / Return Rank: 71
NSIDX Sharpe Ratio Rank: 67
NSIDX Sortino Ratio Rank: 64
NSIDX Omega Ratio Rank: 54
NSIDX Calmar Ratio Rank: 88
NSIDX Martin Ratio Rank: 83

PEXMX

PEXMX Risk / Return Rank: 48
PEXMX Sharpe Ratio Rank: 40
PEXMX Sortino Ratio Rank: 39
PEXMX Omega Ratio Rank: 36
PEXMX Calmar Ratio Rank: 67
PEXMX Martin Ratio Rank: 56

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. PEXMX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Northern Small Cap Index Fund (NSIDX) and T. Rowe Price Extended Equity Market Index Fund (PEXMX). 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	PEXMX	Difference
Sharpe ratio: Return per unit of total volatility	2.20	1.72	+0.49
Sortino ratio: Return per unit of downside risk	3.06	2.43	+0.63
Omega ratio: Gain probability vs. loss probability	1.37	1.29	+0.08
Calmar ratio: Return relative to maximum drawdown	4.07	3.02	+1.06
Martin ratio: Return relative to average drawdown	14.33	10.58	+3.75

NSIDX vs. PEXMX - Sharpe Ratio Comparison

The current NSIDX Sharpe Ratio is 2.20, which is comparable to the PEXMX Sharpe Ratio of 1.72. The chart below compares the historical Sharpe Ratios of NSIDX and PEXMX, 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. PEXMX - Drawdown Comparison

The maximum NSIDX drawdown since its inception was -59.02%, roughly equal to the maximum PEXMX drawdown of -57.82%. Use the drawdown chart below to compare losses from any high point for NSIDX and PEXMX.

Drawdown Indicators

	NSIDX	PEXMX	Difference
Max Drawdown Largest peak-to-trough decline	-59.02%	-57.82%	-1.20%
Max Drawdown (1Y) Largest decline over 1 year	-10.97%	-10.30%	-0.67%
Max Drawdown (3Y) Largest decline over 3 years	-27.71%	-27.01%	-0.70%
Max Drawdown (5Y) Largest decline over 5 years	-32.89%	-36.27%	+3.38%
Max Drawdown (10Y) Largest decline over 10 years	-42.09%	-41.27%	-0.82%
Current Drawdown Current decline from peak	0.00%	-0.22%	+0.22%
Average Drawdown Average peak-to-trough decline	-12.04%	-13.60%	+1.56%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.10%	2.90%	+0.20%

Volatility

NSIDX vs. PEXMX - Volatility Comparison

Northern Small Cap Index Fund (NSIDX) has a higher volatility of 6.40% compared to T. Rowe Price Extended Equity Market Index Fund (PEXMX) at 6.05%. This indicates that NSIDX's price experiences larger fluctuations and is considered to be riskier than PEXMX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	NSIDX	PEXMX	Difference
Volatility (1M) Calculated over the trailing 1-month period	6.40%	6.05%	+0.35%
Volatility (6M) Calculated over the trailing 6-month period	14.44%	13.74%	+0.70%
Volatility (1Y) Calculated over the trailing 1-year period	20.33%	18.15%	+2.18%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	24.31%	22.56%	+1.75%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.31%	22.30%	+2.01%

NSIDX vs. PEXMX - Expense Ratio Comparison

NSIDX has a 0.10% expense ratio, which is lower than PEXMX's 0.23% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

NSIDX vs. PEXMX - Dividend Comparison

NSIDX's dividend yield for the trailing twelve months is around 1.29%, less than PEXMX's 3.49% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
NSIDX Northern Small Cap Index Fund	1.29%	1.57%	6.72%	2.01%	6.38%	12.15%	3.52%	1.78%	12.16%	6.55%	4.06%	6.68%
PEXMX T. Rowe Price Extended Equity Market Index Fund	3.49%	4.02%	7.64%	3.64%	7.53%	14.87%	2.99%	8.17%	6.67%	4.50%	5.90%	4.81%

Frequently Asked Questions

Can I hold both NSIDX and PEXMX in my portfolio?

NSIDX and PEXMX have a correlation of 0.82, 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 PEXMX?

NSIDX has higher volatility (6.40%) compared to PEXMX (6.05%). In terms of maximum drawdown, NSIDX dropped -59.02% vs PEXMX's -57.82%.

Which has better risk-adjusted returns?

NSIDX currently has the higher Sharpe Ratio (2.20 vs 1.72), 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.