PRGMX vs. VLGIX

Last updated Jun 4, 2026

PRGMX (T. Rowe Price GNMA Fund) and VLGIX (Vanguard Long-Term Treasury Index Fund Institutional Shares) are both Government Bonds funds. Over the past 10 years, PRGMX returned 1.31%/yr vs -1.03%/yr for VLGIX. A 0.67 correlation means they provide meaningful diversification when combined. PRGMX charges 0.58%/yr vs 0.05%/yr for VLGIX.

Performance

PRGMX vs. VLGIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in T. Rowe Price GNMA Fund (PRGMX) and Vanguard Long-Term Treasury Index Fund Institutional Shares (VLGIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, PRGMX achieves a 0.93% return, which is significantly higher than VLGIX's -0.22% return. Over the past 10 years, PRGMX has outperformed VLGIX with an annualized return of 1.31%, while VLGIX has yielded a comparatively lower -1.03% annualized return.

PRGMX

• 1D: 0.00%
• 1M: 0.56%
• YTD: 0.93%
• 6M: 1.33%
• 1Y: 7.89%
• 3Y*: 4.84%
• 5Y*: 0.69%
• 10Y*: 1.31%

VLGIX

• 1D: 0.17%
• 1M: 1.13%
• YTD: -0.22%
• 6M: -1.29%
• 1Y: 5.63%
• 3Y*: -0.45%
• 5Y*: -4.92%
• 10Y*: -1.03%

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

PRGMX vs. VLGIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
PRGMX T. Rowe Price GNMA Fund	0.93%	8.72%	1.86%	5.62%	-11.45%	-2.18%	4.21%	5.18%	0.58%	1.23%
VLGIX Vanguard Long-Term Treasury Index Fund Institutional Shares	-0.22%	5.46%	-6.11%	3.67%	-29.45%	-5.06%	17.72%	14.31%	-1.59%	8.64%

Correlation

The correlation between PRGMX and VLGIX is 0.81, 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	0.81
Correlation (3Y) Calculated over the trailing 3-year period	0.86
Correlation (5Y) Calculated over the trailing 5-year period	0.80
Correlation (10Y) Calculated over the trailing 10-year period	0.69
Correlation (All Time) Calculated using the full available price history since Nov 24, 2009	0.67

The correlation between PRGMX and VLGIX shifts across timeframes, from 0.67 (all time) to 0.86 (3 years), reflecting how their relationship changes across market environments.

Return for Risk

PRGMX vs. VLGIX — Risk / Return Rank

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

PRGMX

PRGMX Risk / Return Rank: 44
PRGMX Sharpe Ratio Rank: 42
PRGMX Sortino Ratio Rank: 46
PRGMX Omega Ratio Rank: 43
PRGMX Calmar Ratio Rank: 48
PRGMX Martin Ratio Rank: 41

VLGIX

VLGIX Risk / Return Rank: 7
VLGIX Sharpe Ratio Rank: 7
VLGIX Sortino Ratio Rank: 7
VLGIX Omega Ratio Rank: 7
VLGIX Calmar Ratio Rank: 8
VLGIX Martin Ratio Rank: 7

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.

PRGMX vs. VLGIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for T. Rowe Price GNMA Fund (PRGMX) and Vanguard Long-Term Treasury Index Fund Institutional Shares (VLGIX). 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.

	PRGMX	VLGIX	Difference
Sharpe ratio: Return per unit of total volatility	1.89	0.62	+1.27
Sortino ratio: Return per unit of downside risk	2.86	0.94	+1.92
Omega ratio: Gain probability vs. loss probability	1.36	1.11	+0.25
Calmar ratio: Return relative to maximum drawdown	2.64	0.79	+1.85
Martin ratio: Return relative to average drawdown	8.88	2.06	+6.82
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

PRGMX vs. VLGIX - Sharpe Ratio Comparison

The current PRGMX Sharpe Ratio is 1.89, which is higher than the VLGIX Sharpe Ratio of 0.62. The chart below compares the historical Sharpe Ratios of PRGMX and VLGIX, 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

	PRGMX	VLGIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.89	0.62	+1.27
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.11	-0.34	+0.45
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.28	-0.08	+0.35
Sharpe Ratio (All Time) Calculated using the full available price history	0.93	0.19	+0.74

Drawdowns

PRGMX vs. VLGIX - Drawdown Comparison

The maximum PRGMX drawdown since its inception was -18.22%, smaller than the maximum VLGIX drawdown of -46.23%. Use the drawdown chart below to compare losses from any high point for PRGMX and VLGIX.

Drawdown Indicators

	PRGMX	VLGIX	Difference
Max Drawdown Largest peak-to-trough decline	-18.22%	-46.23%	+28.01%
Max Drawdown (1Y) Largest decline over 1 year	-3.00%	-6.99%	+3.99%
Max Drawdown (3Y) Largest decline over 3 years	-7.14%	-17.65%	+10.51%
Max Drawdown (5Y) Largest decline over 5 years	-17.30%	-41.00%	+23.70%
Max Drawdown (10Y) Largest decline over 10 years	-18.22%	-46.23%	+28.01%
Current Drawdown Current decline from peak	-1.25%	-36.41%	+35.16%
Average Drawdown Average peak-to-trough decline	-2.24%	-15.03%	+12.79%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.89%	2.68%	-1.79%

Volatility

PRGMX vs. VLGIX - Volatility Comparison

The current volatility for T. Rowe Price GNMA Fund (PRGMX) is 1.72%, while Vanguard Long-Term Treasury Index Fund Institutional Shares (VLGIX) has a volatility of 2.69%. This indicates that PRGMX experiences smaller price fluctuations and is considered to be less risky than VLGIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	PRGMX	VLGIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.72%	2.69%	-0.97%
Volatility (6M) Calculated over the trailing 6-month period	3.11%	6.07%	-2.96%
Volatility (1Y) Calculated over the trailing 1-year period	4.20%	8.98%	-4.78%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.38%	14.56%	-8.18%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.77%	13.72%	-8.95%

PRGMX vs. VLGIX - Expense Ratio Comparison

PRGMX has a 0.58% expense ratio, which is higher than VLGIX's 0.05% expense ratio.

Dividends

PRGMX vs. VLGIX - Dividend Comparison

PRGMX's dividend yield for the trailing twelve months is around 4.99%, more than VLGIX's 4.59% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
PRGMX T. Rowe Price GNMA Fund	4.99%	4.96%	4.47%	3.54%	1.38%	0.59%	1.44%	2.39%	2.78%	2.98%	2.88%	3.12%
VLGIX Vanguard Long-Term Treasury Index Fund Institutional Shares	4.59%	4.43%	4.67%	3.31%	2.83%	1.78%	2.15%	2.46%	2.73%	2.57%	2.70%	2.82%

Frequently Asked Questions

Can I hold both PRGMX and VLGIX in my portfolio?

PRGMX and VLGIX have a correlation of 0.81, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, PRGMX or VLGIX?

VLGIX has higher volatility (2.69%) compared to PRGMX (1.72%). In terms of maximum drawdown, PRGMX dropped -18.22% vs VLGIX's -46.23%.

Which has better risk-adjusted returns?

PRGMX currently has the higher Sharpe Ratio (1.89 vs 0.62), 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.