PREIX vs. PRCOX

Last updated Jun 4, 2026

PREIX (T. Rowe Price Equity Index 500 Fund) and PRCOX (T. Rowe Price U.S. Equity Research Fund) are both Large Cap Blend Equities funds from T. Rowe Price. Over the past 10 years, PREIX returned 15.42%/yr vs 16.17%/yr for PRCOX. With a 0.96 correlation, they move nearly in lockstep. PREIX charges 0.15%/yr vs 0.42%/yr for PRCOX.

Performance

PREIX vs. PRCOX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in T. Rowe Price Equity Index 500 Fund (PREIX) and T. Rowe Price U.S. Equity Research Fund (PRCOX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

The year-to-date returns for both investments are quite close, with PREIX having a 11.61% return and PRCOX slightly higher at 12.08%. Both investments have delivered pretty close results over the past 10 years, with PREIX having a 15.42% annualized return and PRCOX not far ahead at 16.17%.

PREIX

• 1D: 0.13%
• 1M: 5.78%
• YTD: 11.61%
• 6M: 11.63%
• 1Y: 28.74%
• 3Y*: 22.53%
• 5Y*: 14.08%
• 10Y*: 15.42%

PRCOX

• 1D: 0.28%
• 1M: 5.68%
• YTD: 12.08%
• 6M: 12.15%
• 1Y: 28.46%
• 3Y*: 23.19%
• 5Y*: 14.72%
• 10Y*: 16.17%

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

PREIX vs. PRCOX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
PREIX T. Rowe Price Equity Index 500 Fund	11.61%	17.66%	24.78%	26.07%	-18.27%	28.48%	18.17%	31.47%	-4.59%	21.01%
PRCOX T. Rowe Price U.S. Equity Research Fund	12.08%	16.34%	26.41%	29.82%	-18.80%	28.06%	19.82%	33.04%	-4.73%	23.80%

Correlation

The correlation between PREIX and PRCOX is 0.97 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.97
Correlation (3Y) Calculated over the trailing 3-year period	0.99
Correlation (5Y) Calculated over the trailing 5-year period	0.99
Correlation (10Y) Calculated over the trailing 10-year period	0.99
Correlation (All Time) Calculated using the full available price history since Jan 4, 1995	0.96

The correlation between PREIX and PRCOX has been stable across timeframes, ranging from 0.96 to 0.99 - a consistent structural relationship.

Return for Risk

PREIX vs. PRCOX — Risk / Return Rank

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

PREIX

PREIX Risk / Return Rank: 72
PREIX Sharpe Ratio Rank: 74
PREIX Sortino Ratio Rank: 66
PREIX Omega Ratio Rank: 66
PREIX Calmar Ratio Rank: 73
PREIX Martin Ratio Rank: 82

PRCOX

PRCOX Risk / Return Rank: 69
PRCOX Sharpe Ratio Rank: 72
PRCOX Sortino Ratio Rank: 67
PRCOX Omega Ratio Rank: 63
PRCOX Calmar Ratio Rank: 67
PRCOX Martin Ratio Rank: 78

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.

PREIX vs. PRCOX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for T. Rowe Price Equity Index 500 Fund (PREIX) and T. Rowe Price U.S. Equity Research Fund (PRCOX). 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.

	PREIX	PRCOX	Difference
Sharpe ratio: Return per unit of total volatility	2.50	2.47	+0.03
Sortino ratio: Return per unit of downside risk	3.40	3.42	-0.02
Omega ratio: Gain probability vs. loss probability	1.45	1.44	+0.01
Calmar ratio: Return relative to maximum drawdown	3.32	3.16	+0.16
Martin ratio: Return relative to average drawdown	15.47	14.73	+0.74
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

PREIX vs. PRCOX - Sharpe Ratio Comparison

The current PREIX Sharpe Ratio is 2.50, which is comparable to the PRCOX Sharpe Ratio of 2.47. The chart below compares the historical Sharpe Ratios of PREIX and PRCOX, 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

	PREIX	PRCOX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.50	2.47	+0.03
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.83	0.85	-0.02
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.85	0.88	-0.03
Sharpe Ratio (All Time) Calculated using the full available price history	0.61	0.57	+0.04

Drawdowns

PREIX vs. PRCOX - Drawdown Comparison

The maximum PREIX drawdown since its inception was -55.32%, roughly equal to the maximum PRCOX drawdown of -53.96%. Use the drawdown chart below to compare losses from any high point for PREIX and PRCOX.

Drawdown Indicators

	PREIX	PRCOX	Difference
Max Drawdown Largest peak-to-trough decline	-55.32%	-53.96%	-1.36%
Max Drawdown (1Y) Largest decline over 1 year	-8.93%	-9.32%	+0.39%
Max Drawdown (3Y) Largest decline over 3 years	-18.78%	-19.39%	+0.61%
Max Drawdown (5Y) Largest decline over 5 years	-24.60%	-24.94%	+0.34%
Max Drawdown (10Y) Largest decline over 10 years	-33.81%	-34.42%	+0.61%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-8.73%	-9.18%	+0.45%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.91%	1.99%	-0.08%

Volatility

PREIX vs. PRCOX - Volatility Comparison

The current volatility for T. Rowe Price Equity Index 500 Fund (PREIX) is 2.83%, while T. Rowe Price U.S. Equity Research Fund (PRCOX) has a volatility of 3.07%. This indicates that PREIX experiences smaller price fluctuations and is considered to be less risky than PRCOX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	PREIX	PRCOX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.83%	3.07%	-0.24%
Volatility (6M) Calculated over the trailing 6-month period	8.98%	9.39%	-0.41%
Volatility (1Y) Calculated over the trailing 1-year period	11.87%	11.93%	-0.06%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	17.00%	17.34%	-0.34%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.11%	18.35%	-0.24%

PREIX vs. PRCOX - Expense Ratio Comparison

PREIX has a 0.15% expense ratio, which is lower than PRCOX's 0.42% expense ratio.

Dividends

PREIX vs. PRCOX - Dividend Comparison

PREIX's dividend yield for the trailing twelve months is around 2.10%, more than PRCOX's 1.05% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
PRCOX T. Rowe Price U.S. Equity Research Fund	1.05%	1.17%	0.64%	1.17%	1.28%	3.71%	1.04%	1.39%	5.60%	7.02%	7.28%	8.76%
PREIX T. Rowe Price Equity Index 500 Fund	2.10%	2.32%	1.17%	1.32%	1.50%	1.56%	1.97%	2.13%	2.60%	1.30%	2.03%	2.02%

Frequently Asked Questions

Can I hold both PREIX and PRCOX in my portfolio?

With a correlation of 0.97, PREIX and PRCOX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.

Which is riskier, PREIX or PRCOX?

PRCOX has higher volatility (3.07%) compared to PREIX (2.83%). In terms of maximum drawdown, PREIX dropped -55.32% vs PRCOX's -53.96%.

Which has better risk-adjusted returns?

PREIX currently has the higher Sharpe Ratio (2.50 vs 2.47), 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.