Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX)



Options Expense ratio Minimum
Admiral 0.12% N/A
Inst 0.09% $5,000,000
ETF 0.12% Note

Vanguard ETF Shares can be bought and sold only through a broker (who may charge a commission) and cannot be redeemed with the issuing fund. The market price of Vanguard ETF Shares may be more or less than net asset value.

About our options  



Purchase fee:

A fee charged by some mutual funds when an investor buys shares. This fee is not a sales charge or load because it is paid directly to the fund to offset the costs of trading certain securities.

Redemption fee:

A fee charged by some mutual funds when an investor sells shares. A redemption fee differs from a back-end load because the money is paid back into the fund. Many funds charge redemption fees only when shares are bought and then sold within a specific period of time, generally in an effort to discourage market-timing and short-term trading. Some brokers also charge their clients redemption fees for the sale of securities.



Designation: Intermediate Government
 inception on 12/03/2009
Earliest share class inception on 11/19/2009
$803.4 million total net assets

This represents the total net assets for all share classes of Vanguard's U.S. funds, as well as any collective trust that shares the same investment strategy, management and holdings.

 as of 03/31/2014
$287.9 million net assets for
 as of 03/31/2014
443 holdings as of 03/31/2014
Indexed to the Barclays US MBS Float Adj Index (LMBGTRUU)
Turnover rate (Fiscal year-end  08/31/2013) 840.00%


Portfolio of mortgage-backed securities.

Expected range
Central tendency

About our styleboxes  

Investment approach

  • Seeks to track the performance of the Barclays U.S. Mortgage Backed Securities Float Adjusted Index.
  • Diversified exposure to the intermediate-term U.S. mortgage-backed securities market.
  • Follows a passively managed, index-sampling approach.
  • Provides current income with high credit quality.

Total returns

View as:

as of 03/31/2014

  1 year 3 year 5 year 10 year Since inception


0.23% 2.69% 3.00%

Barclays U.S. MBS Float Adjusted Index

0.49% 2.81%

Note: Fee adjusted for mutual funds where applicable.

* Includes U.S. agency mortgage-backed pass-through securities.

The performance data shown represent past performance, which is not a guarantee of future results. Investment returns and principal value will fluctuate, so investors' shares, when sold, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data cited.

Distribution by credit quality(% of fund) as of 03/31/2014

  Credit rating  VMBSX
U.S. Government 100.0%
Aaa 0.0%
Aa 0.0%
A 0.0%
Baa 0.0%
< Baa 0.0%
Total 100.0%
* Credit-quality ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). “NR” is used to classify securities for which a rating is not available. U.S. Treasury, U.S. Agency, and U.S. Agency mortgage-backed securities appear under “U.S. Government.” Credit-quality ratings for each issue are obtained from Barclays using ratings derived from Moody’s Investors Service, Fitch Ratings, and Standard & Poor’s. When ratings from all three agencies are available, the median rating is used. When ratings are available from two of the agencies, the lower rating is used. When one rating is available, that rating is used.


Bondas of 03/31/2014 VMBSX Benchmark

Barclays U.S. MBS Float Adjusted Index

Number of bonds 443 765
Yield to maturity 3.04% 3.05%
Short-term reserves 0.00% N/A
Average duration 5.1 (years) 5.2 (years)
Average maturity 7.1 (years) 7.2 (years)
Average coupon 4.03% 4.02%

Risk and volatility as of 03/31/2014

  VMBSX Benchmark

Barclays U.S. MBS Float Adjusted Index

R-squared N/A 0.99
Beta N/A 1.07
Alpha – 0.02 N/A
Standard deviation 2.21% 2.05%
Sharpe ratio 1.19 1.34

Risk and volatility are based on the share class with the earliest inception date.

Risk measures are calculated from trailing 36-month fund returns relative to the associated benchmarks.

An investment in the fund could lose money over short or even long periods. You should expect the fund’s share price and total return to fluctuate within a wide range, like the fluctuations of the overall bond market. The fund’s performance could be hurt by:

  • Interest rate risk: The chance that bond prices overall will decline because of rising interest rates.
  • Income risk: The chance that the fund’s income will decline because of falling interest rates.
  • Prepayment risk: The chance that during periods of falling interest rates, homeowners will refinance their mortgages before their maturity dates, resulting in prepayment of mortgage securities held by the fund. The fund would then lose potential price appreciation and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the fund’s income. Prepayment risk is high for the fund.
  • Index sampling risk: The chance that the securities selected for the fund, in the aggregate, will not provide investment performance matching that of the index. Index sampling risk for the fund should be low.


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