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GNMA vs. SPMB
Performance
Return for Risk
Drawdowns
Volatility
Dividends

GNMA vs. SPMB

Last updated Jun 4, 2026

GNMA (iShares GNMA Bond ETF) and SPMB (SPDR Portfolio Mortgage Backed Bond ETF) are both Mortgage Backed Securities funds - GNMA tracks the Barclays Capital GNMA Index while SPMB tracks the Bloomberg US Aggregate Securitized - MBS. Both are passively managed. Over the past 10 years, GNMA returned 1.23%/yr vs 1.21%/yr for SPMB. A 0.61 correlation means they provide meaningful diversification when combined. GNMA charges 0.15%/yr vs 0.04%/yr for SPMB.

Performance

GNMA vs. SPMB - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in iShares GNMA Bond ETF (GNMA) and SPDR Portfolio Mortgage Backed Bond ETF (SPMB). The values are adjusted to include any dividend payments, if applicable.

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Returns By Period

In the year-to-date period, GNMA achieves a 0.56% return, which is significantly higher than SPMB's 0.51% return. Both investments have delivered pretty close results over the past 10 years, with GNMA having a 1.23% annualized return and SPMB not far behind at 1.21%.

GNMA

1D
-0.19%
1M
-0.07%
YTD
0.56%
6M
0.81%
1Y
6.56%
3Y*
4.20%
5Y*
0.53%
10Y*
1.23%

SPMB

1D
-0.22%
1M
0.27%
YTD
0.51%
6M
0.64%
1Y
6.74%
3Y*
4.32%
5Y*
0.29%
10Y*
1.21%
*Multi-year figures are annualized to reflect compound growth (CAGR)

GNMA vs. SPMB - Yearly Performance Comparison

2026 (YTD)202520242023202220212020201920182017
GNMA
iShares GNMA Bond ETF		0.56%8.25%1.07%5.34%-10.83%-1.86%3.51%5.85%0.85%1.74%
SPMB
SPDR Portfolio Mortgage Backed Bond ETF		0.51%8.29%1.35%5.09%-12.05%-1.46%4.19%6.16%1.01%2.13%

Correlation

The correlation between GNMA and SPMB 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

0.91

Correlation (10Y)
Calculated over the trailing 10-year period

0.75

Correlation (All Time)
Calculated using the full available price history since Feb 22, 2012

0.61

Over the past year, GNMA and SPMB have become more correlated (0.82) than their long-term average of 0.61, meaning their price movements have been converging.

Compare stocks, funds, or ETFs

Search for stocks, ETFs, and funds for a quick comparison or use the comparison tool for more options.

iShares GNMA Bond ETF

SPDR Portfolio Mortgage Backed Bond ETF

Often compared with GNMA:
GNMA vs. TFIGNMA vs. VMBSGNMA vs. FLIAGNMA vs. BAGIXGNMA vs. VOOGNMA vs. GOVTGNMA vs. LMBS
Often compared with SPMB:
SPMB vs. VMBSSPMB vs. SPTISPMB vs. MBSDSPMB vs. GSSTSPMB vs. BNDSPMB vs. QQQSPMB vs. SCHG

Return for Risk

GNMA vs. SPMB — Risk / Return Rank

Compare risk-adjusted metric ranks to identify better-performing investments over the past 12 months.
GNMA
GNMA Risk / Return Rank: 4646
Overall Rank
GNMA Sharpe Ratio Rank: 4444
Sharpe Ratio Rank
GNMA Sortino Ratio Rank: 4747
Sortino Ratio Rank
GNMA Omega Ratio Rank: 4242
Omega Ratio Rank
GNMA Calmar Ratio Rank: 5151
Calmar Ratio Rank
GNMA Martin Ratio Rank: 4848
Martin Ratio Rank
SPMB
SPMB Risk / Return Rank: 4747
Overall Rank
SPMB Sharpe Ratio Rank: 4545
Sharpe Ratio Rank
SPMB Sortino Ratio Rank: 4848
Sortino Ratio Rank
SPMB Omega Ratio Rank: 4646
Omega Ratio Rank
SPMB Calmar Ratio Rank: 4747
Calmar Ratio Rank
SPMB Martin Ratio Rank: 4747
Martin Ratio Rank
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.

GNMA vs. SPMB - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for iShares GNMA Bond ETF (GNMA) and SPDR Portfolio Mortgage Backed Bond ETF (SPMB). 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.

GNMASPMBDifference

Sharpe ratio

Return per unit of total volatility

1.53

1.58

-0.05

Sortino ratio

Return per unit of downside risk

2.35

2.37

-0.02

Omega ratio

Gain probability vs. loss probability

1.27

1.29

-0.01

Calmar ratio

Return relative to maximum drawdown

2.52

2.34

+0.18

Martin ratio

Return relative to average drawdown

8.05

7.70

+0.35

Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

GNMA vs. SPMB - Sharpe Ratio Comparison

The current GNMA Sharpe Ratio is 1.53, which is comparable to the SPMB Sharpe Ratio of 1.58. The chart below compares the historical Sharpe Ratios of GNMA and SPMB, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

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Sharpe Ratios by Period

GNMASPMBDifference

Sharpe Ratio (1Y)

Calculated over the trailing 1-year period

1.53

1.58

-0.05

Sharpe Ratio (5Y)

Calculated over the trailing 5-year period

0.08

0.04

+0.04

Sharpe Ratio (10Y)

Calculated over the trailing 10-year period

0.24

0.16

+0.08

Sharpe Ratio (All Time)

Calculated using the full available price history

0.25

0.34

-0.09

Drawdowns

GNMA vs. SPMB - Drawdown Comparison

The maximum GNMA drawdown since its inception was -17.09%, smaller than the maximum SPMB drawdown of -18.03%. Use the drawdown chart below to compare losses from any high point for GNMA and SPMB.

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Drawdown Indicators

GNMASPMBDifference

Max Drawdown

Largest peak-to-trough decline

-17.09%

-18.03%

+0.94%

Max Drawdown (1Y)

Largest decline over 1 year

-2.61%

-2.89%

+0.28%

Max Drawdown (3Y)

Largest decline over 3 years

-7.13%

-7.66%

+0.53%

Max Drawdown (5Y)

Largest decline over 5 years

-15.83%

-17.49%

+1.66%

Max Drawdown (10Y)

Largest decline over 10 years

-17.09%

-18.03%

+0.94%

Current Drawdown

Current decline from peak

-1.41%

-1.58%

+0.17%

Average Drawdown

Average peak-to-trough decline

-3.66%

-2.85%

-0.81%

Ulcer Index

Depth and duration of drawdowns from previous peaks

0.82%

0.88%

-0.06%

Volatility

GNMA vs. SPMB - Volatility Comparison

iShares GNMA Bond ETF (GNMA) and SPDR Portfolio Mortgage Backed Bond ETF (SPMB) have volatilities of 1.54% and 1.58%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.

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Volatility by Period

GNMASPMBDifference

Volatility (1M)

Calculated over the trailing 1-month period

1.54%

1.58%

-0.04%

Volatility (6M)

Calculated over the trailing 6-month period

3.14%

3.08%

+0.06%

Volatility (1Y)

Calculated over the trailing 1-year period

4.30%

4.28%

+0.02%

Volatility (5Y)

Calculated over the trailing 5-year period, annualized

6.61%

6.77%

-0.16%

Volatility (10Y)

Calculated over the trailing 10-year period, annualized

5.13%

7.61%

-2.48%

GNMA vs. SPMB - Expense Ratio Comparison

GNMA has a 0.15% expense ratio, which is higher than SPMB's 0.04% 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

GNMA vs. SPMB - Dividend Comparison

GNMA's dividend yield for the trailing twelve months is around 4.24%, more than SPMB's 4.09% yield.

PositionTTM20252024202320222021202020192018201720162015
GNMA
iShares GNMA Bond ETF		4.24%4.19%4.15%3.43%2.01%0.64%1.89%2.61%2.41%2.15%1.89%1.50%
SPMB
SPDR Portfolio Mortgage Backed Bond ETF		4.09%3.98%3.76%3.21%2.98%2.59%2.95%3.24%3.36%3.13%2.99%3.05%

Frequently Asked Questions

GNMA and SPMB 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.

SPMB has higher volatility (1.58%) compared to GNMA (1.54%). In terms of maximum drawdown, GNMA dropped -17.09% vs SPMB's -18.03%.

On 10-year performance, GNMA leads with 1.23% vs 1.21% for SPMB. On fees, SPMB is cheaper at 0.04% per year. Their volatility is very similar. The better choice depends on whether you care most about return, fees, risk, or income.

Over the 10-year period, GNMA has performed better with a 1.23% return vs 1.21%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.

SPMB is cheaper with a 0.04% expense ratio, compared with 0.15% for GNMA.

GNMA has the higher dividend yield at 4.24%, compared with 4.09% for SPMB.

GNMA tracks Barclays Capital GNMA Index, while SPMB tracks Bloomberg US Aggregate Securitized - MBS. They also come from different issuers: iShares and State Street. Their fees differ too: 0.15% for GNMA and 0.04% for SPMB.

SPMB currently has the higher Sharpe Ratio (1.58 vs 1.53), 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.

Portfolio Optimizer

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