PEXMX vs. NSIDX

Last updated Jun 4, 2026

PEXMX (T. Rowe Price Extended Equity Market Index Fund) and NSIDX (Northern Small Cap Index Fund) are both mutual funds - PEXMX is a Mid Cap Growth Equities fund managed by T. Rowe Price, while NSIDX is a Small Cap Blend Equities fund managed by Northern Funds. Over the past 10 years, PEXMX returned 12.22%/yr vs 10.98%/yr for NSIDX. With a 0.96 correlation, they move nearly in lockstep. PEXMX charges 0.23%/yr vs 0.10%/yr for NSIDX.

Performance

PEXMX vs. NSIDX - Performance Comparison

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

Returns By Period

In the year-to-date period, PEXMX achieves a 14.63% return, which is significantly lower than NSIDX's 18.68% return. Over the past 10 years, PEXMX has outperformed NSIDX with an annualized return of 12.22%, while NSIDX has yielded a comparatively lower 10.98% annualized return.

PEXMX

• 1D: 1.08%
• 1M: 5.79%
• YTD: 14.63%
• 6M: 13.30%
• 1Y: 29.74%
• 3Y*: 19.87%
• 5Y*: 6.84%
• 10Y*: 12.22%

NSIDX

• 1D: 0.93%
• 1M: 4.97%
• YTD: 18.68%
• 6M: 17.43%
• 1Y: 41.27%
• 3Y*: 18.61%
• 5Y*: 6.47%
• 10Y*: 10.98%

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

PEXMX vs. NSIDX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
PEXMX T. Rowe Price Extended Equity Market Index Fund	14.63%	11.17%	16.72%	25.32%	-26.15%	12.09%	30.80%	32.57%	-9.61%	16.63%
NSIDX Northern Small Cap Index Fund	18.68%	12.88%	11.45%	16.87%	-20.63%	14.38%	19.59%	25.22%	-11.33%	14.62%

Correlation

The correlation between PEXMX and NSIDX 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 7, 1999	0.96

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

Return for Risk

PEXMX vs. NSIDX — Risk / Return Rank

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

PEXMX

PEXMX Risk / Return Rank: 48
PEXMX Sharpe Ratio Rank: 41
PEXMX Sortino Ratio Rank: 40
PEXMX Omega Ratio Rank: 37
PEXMX Calmar Ratio Rank: 67
PEXMX Martin Ratio Rank: 55

NSIDX

NSIDX Risk / Return Rank: 65
NSIDX Sharpe Ratio Rank: 58
NSIDX Sortino Ratio Rank: 56
NSIDX Omega Ratio Rank: 49
NSIDX Calmar Ratio Rank: 85
NSIDX Martin Ratio Rank: 75

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.

PEXMX vs. NSIDX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for T. Rowe Price Extended Equity Market Index Fund (PEXMX) and Northern Small Cap Index Fund (NSIDX). 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.

	PEXMX	NSIDX	Difference
Sharpe ratio: Return per unit of total volatility	1.86	2.25	-0.38
Sortino ratio: Return per unit of downside risk	2.64	3.15	-0.51
Omega ratio: Gain probability vs. loss probability	1.32	1.38	-0.06
Calmar ratio: Return relative to maximum drawdown	3.17	4.05	-0.88
Martin ratio: Return relative to average drawdown	11.18	14.27	-3.09
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

PEXMX vs. NSIDX - Sharpe Ratio Comparison

The current PEXMX Sharpe Ratio is 1.86, which is comparable to the NSIDX Sharpe Ratio of 2.25. The chart below compares the historical Sharpe Ratios of PEXMX and NSIDX, 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

	PEXMX	NSIDX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.86	2.25	-0.38
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.31	0.27	+0.04
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.55	0.45	+0.10
Sharpe Ratio (All Time) Calculated using the full available price history	0.40	0.34	+0.06

Drawdowns

PEXMX vs. NSIDX - Drawdown Comparison

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

Drawdown Indicators

	PEXMX	NSIDX	Difference
Max Drawdown Largest peak-to-trough decline	-57.82%	-59.02%	+1.20%
Max Drawdown (1Y) Largest decline over 1 year	-10.30%	-10.97%	+0.67%
Max Drawdown (3Y) Largest decline over 3 years	-27.01%	-27.71%	+0.70%
Max Drawdown (5Y) Largest decline over 5 years	-36.27%	-32.89%	-3.38%
Max Drawdown (10Y) Largest decline over 10 years	-41.27%	-42.09%	+0.82%
Current Drawdown Current decline from peak	0.00%	-0.11%	+0.11%
Average Drawdown Average peak-to-trough decline	-13.62%	-12.06%	-1.56%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.88%	3.09%	-0.21%

Volatility

PEXMX vs. NSIDX - Volatility Comparison

The current volatility for T. Rowe Price Extended Equity Market Index Fund (PEXMX) is 4.68%, while Northern Small Cap Index Fund (NSIDX) has a volatility of 5.61%. This indicates that PEXMX experiences smaller price fluctuations and is considered to be less risky than NSIDX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	PEXMX	NSIDX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.68%	5.61%	-0.93%
Volatility (6M) Calculated over the trailing 6-month period	13.24%	13.67%	-0.43%
Volatility (1Y) Calculated over the trailing 1-year period	17.49%	19.77%	-2.28%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.46%	24.23%	-1.77%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	22.25%	24.26%	-2.01%

PEXMX vs. NSIDX - Expense Ratio Comparison

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

Dividends

PEXMX vs. NSIDX - Dividend Comparison

PEXMX's dividend yield for the trailing twelve months is around 3.51%, more than NSIDX's 1.33% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
NSIDX Northern Small Cap Index Fund	1.33%	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	3.51%	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 PEXMX and NSIDX in my portfolio?

PEXMX and NSIDX 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, PEXMX or NSIDX?

NSIDX has higher volatility (5.61%) compared to PEXMX (4.68%). In terms of maximum drawdown, PEXMX dropped -57.82% vs NSIDX's -59.02%.

Which has better risk-adjusted returns?

NSIDX currently has the higher Sharpe Ratio (2.25 vs 1.86), 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.