TIDDX vs. PREIX

Last updated Jun 4, 2026

TIDDX (T. Rowe Price International Discovery Fund Class I) and PREIX (T. Rowe Price Equity Index 500 Fund) are both mutual funds - TIDDX is a Foreign Small & Mid Cap Equities fund tracking the S&P Global ex-U.S. Small Cap Index Net, while PREIX is a Large Cap Blend Equities fund managed by T. Rowe Price. Over the past 10 years, TIDDX returned 9.15%/yr vs 15.42%/yr for PREIX. A 0.74 correlation means they provide meaningful diversification when combined. TIDDX charges 1.08%/yr vs 0.15%/yr for PREIX.

Performance

TIDDX vs. PREIX - Performance Comparison

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

Returns By Period

In the year-to-date period, TIDDX achieves a 8.94% return, which is significantly lower than PREIX's 11.61% return. Over the past 10 years, TIDDX has underperformed PREIX with an annualized return of 9.15%, while PREIX has yielded a comparatively higher 15.42% annualized return.

TIDDX

• 1D: 0.10%
• 1M: 2.25%
• YTD: 8.94%
• 6M: 12.53%
• 1Y: 22.76%
• 3Y*: 15.24%
• 5Y*: 2.30%
• 10Y*: 9.15%

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%

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

TIDDX vs. PREIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
TIDDX T. Rowe Price International Discovery Fund Class I	8.94%	25.73%	3.81%	13.38%	-30.23%	7.45%	38.95%	25.18%	-17.42%	38.58%
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%

Correlation

The correlation between TIDDX and PREIX is 0.72, 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	0.72
Correlation (3Y) Calculated over the trailing 3-year period	0.71
Correlation (5Y) Calculated over the trailing 5-year period	0.74
Correlation (10Y) Calculated over the trailing 10-year period	0.74
Correlation (All Time) Calculated using the full available price history since Jan 5, 2016	0.74

The correlation between TIDDX and PREIX has been stable across timeframes, ranging from 0.71 to 0.74 - a consistent structural relationship.

Return for Risk

TIDDX vs. PREIX — Risk / Return Rank

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

TIDDX

TIDDX Risk / Return Rank: 27
TIDDX Sharpe Ratio Rank: 30
TIDDX Sortino Ratio Rank: 28
TIDDX Omega Ratio Rank: 30
TIDDX Calmar Ratio Rank: 20
TIDDX Martin Ratio Rank: 25

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

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.

TIDDX vs. PREIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for T. Rowe Price International Discovery Fund Class I (TIDDX) and T. Rowe Price Equity Index 500 Fund (PREIX). 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.

	TIDDX	PREIX	Difference
Sharpe ratio: Return per unit of total volatility	1.57	2.50	-0.93
Sortino ratio: Return per unit of downside risk	2.23	3.40	-1.17
Omega ratio: Gain probability vs. loss probability	1.29	1.45	-0.17
Calmar ratio: Return relative to maximum drawdown	1.65	3.32	-1.67
Martin ratio: Return relative to average drawdown	6.11	15.47	-9.36
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

TIDDX vs. PREIX - Sharpe Ratio Comparison

The current TIDDX Sharpe Ratio is 1.57, which is lower than the PREIX Sharpe Ratio of 2.50. The chart below compares the historical Sharpe Ratios of TIDDX and PREIX, 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

	TIDDX	PREIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.57	2.50	-0.93
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.14	0.83	-0.69
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.55	0.85	-0.30
Sharpe Ratio (All Time) Calculated using the full available price history	0.55	0.61	-0.06

Drawdowns

TIDDX vs. PREIX - Drawdown Comparison

The maximum TIDDX drawdown since its inception was -43.76%, smaller than the maximum PREIX drawdown of -55.32%. Use the drawdown chart below to compare losses from any high point for TIDDX and PREIX.

Drawdown Indicators

	TIDDX	PREIX	Difference
Max Drawdown Largest peak-to-trough decline	-43.76%	-55.32%	+11.56%
Max Drawdown (1Y) Largest decline over 1 year	-13.50%	-8.93%	-4.57%
Max Drawdown (3Y) Largest decline over 3 years	-15.81%	-18.78%	+2.97%
Max Drawdown (5Y) Largest decline over 5 years	-43.76%	-24.60%	-19.16%
Max Drawdown (10Y) Largest decline over 10 years	-43.76%	-33.81%	-9.95%
Current Drawdown Current decline from peak	-1.28%	0.00%	-1.28%
Average Drawdown Average peak-to-trough decline	-13.20%	-8.73%	-4.47%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.63%	1.91%	+1.72%

Volatility

TIDDX vs. PREIX - Volatility Comparison

T. Rowe Price International Discovery Fund Class I (TIDDX) has a higher volatility of 3.87% compared to T. Rowe Price Equity Index 500 Fund (PREIX) at 2.83%. This indicates that TIDDX's price experiences larger fluctuations and is considered to be riskier than PREIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	TIDDX	PREIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.87%	2.83%	+1.04%
Volatility (6M) Calculated over the trailing 6-month period	11.70%	8.98%	+2.72%
Volatility (1Y) Calculated over the trailing 1-year period	14.18%	11.87%	+2.31%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.71%	17.00%	-0.29%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	16.64%	18.11%	-1.47%

TIDDX vs. PREIX - Expense Ratio Comparison

TIDDX has a 1.08% expense ratio, which is higher than PREIX's 0.15% expense ratio.

Dividends

TIDDX vs. PREIX - Dividend Comparison

TIDDX's dividend yield for the trailing twelve months is around 4.85%, more than PREIX's 2.10% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
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%
TIDDX T. Rowe Price International Discovery Fund Class I	4.85%	5.28%	4.36%	2.24%	3.17%	15.55%	4.39%	1.51%	6.38%	3.11%	2.50%	0.00%

Frequently Asked Questions

Can I hold both TIDDX and PREIX in my portfolio?

TIDDX and PREIX have a correlation of 0.72, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, TIDDX or PREIX?

TIDDX has higher volatility (3.87%) compared to PREIX (2.83%). In terms of maximum drawdown, TIDDX dropped -43.76% vs PREIX's -55.32%.

Which has better risk-adjusted returns?

PREIX currently has the higher Sharpe Ratio (2.50 vs 1.57), 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.