Principal Investment Strategies
To pursue its goal, the fund generally invests in securities
that are included in the Bloomberg Barclays US Aggregate Bond Index†. The index is a broad-based benchmark
measuring the performance of the U.S. investment grade, taxable bond market, including U.S. Treasuries, government-related and corporate bonds, mortgage pass-through securities, commercial mortgage-backed securities, and asset-backed securities that
are publicly available for sale in the United States. To be eligible for inclusion in the index, securities must be fixed-rate, non-convertible, U.S. dollar denominated with at least $300 million or more of outstanding face value and have one or
more years remaining to maturity. The index excludes certain types of securities, including tax-exempt state and local government series bonds, structured notes embedded with swaps or other special features, private placements, floating-rate
securities, inflation-linked bonds and Eurobonds. The index is market capitalization weighted and the securities in the index are updated on the last business day of each month. As of December 31, 2018, there were approximately 10,248 securities in
the index.
It is the fund’s policy that
under normal circumstances it will invest at least 90% of its net assets (including, for this purpose, any borrowings for investment purposes) in securities included in the index, including TBA transactions, as defined below. The fund will notify
its shareholders at least 60 days before changing this policy.
Under normal circumstances, the fund may invest up to 10% of
its net assets in securities not included in its index. The principal types of these investments include those that the investment adviser believes will help the fund track the index, such as investments in (a) securities that are not represented in
the index but the investment adviser anticipates will be added to the index; (b) high-quality liquid short-term investments, such as securities issued by the U.S. government, its agencies or instrumentalities, including obligations that are not
guaranteed by the U.S. Treasury, and obligations that are issued by private issuers that are guaranteed as to principal or interest by the U.S. government, its agencies or instrumentalities; (c) other investment companies; and (d) derivatives,
principally futures contracts. The fund may use futures contracts and other derivatives primarily to help manage interest rate exposure. The fund may also invest in cash and cash equivalents, including money market funds, and lend its securities to
minimize the difference in performance that naturally exists between an index fund and its corresponding index.
Because it is not possible or practical to purchase all of the
securities in the index, the fund’s investment adviser will seek to track the total return of the index by using sampling techniques. Sampling techniques involve investing in a limited number of index securities that, when taken together, are
expected to perform similarly to the index as a whole. These techniques are based on a variety of factors, including interest rate and yield curve risk, maturity exposures, industry, sector and issuer weights, credit
quality, and other risk factors and characteristics. The fund expects that
its portfolio will hold less than the total number of securities in the index, but reserves the right to hold as many securities as it believes necessary to achieve the fund’s investment objective. The fund generally expects that its weighted
average duration will closely correspond to the weighted average duration of the index, which as of December 31, 2018, was 5.81 years.
As of December 31, 2018, approximately 28.21% of the bonds
represented in the index were U.S. fixed-rate agency mortgage pass-through securities. U.S. fixed-rate agency mortgage pass-through securities are securities issued by entities such as the Government National Mortgage Association (Ginnie Mae), the
Federal National Mortgage Association (Fannie Mae), and the Federal Home Loan Mortgage Corporation (Freddie Mac) that are backed by pools of mortgages. Most transactions in fixed-rate mortgage pass-through securities occur through standardized
contracts for future delivery in which the exact mortgage pools to be delivered are not specified until a few days prior to settlement, and are often referred to as “to-be-announced transactions” or “TBA transactions.” In a
TBA transaction, the buyer and seller agree upon general trade parameters such as agency, settlement date, par amount and price. The actual pools delivered generally are determined two days prior to settlement date; however, it is not anticipated
that the fund will receive the pools, but will instead participate in rolling TBA transactions. The fund anticipates that it may enter into such contracts on a regular basis. This may result in a significantly higher portfolio turnover for the fund
than a typical index fund. The fund, pending settlement of such contracts, will invest its assets in high-quality liquid short-term instruments, including Treasury securities and shares of money market mutual funds. The fund will assume its pro rata
share of the fees and expenses of any money market fund that it may invest in, in addition to the fund’s own fees and expenses.
The fund will concentrate its investments (i.e., hold 25% or
more of its total assets) in a particular industry, group of industries or sector to approximately the same extent that its index is so concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and
instrumentalities), and repurchase agreements collateralized by U.S. government securities are not considered to be issued by members of any industry.
The investment adviser seeks to achieve, over time, a
correlation between the fund’s performance and that of its index, before fees and expenses, of 95% or better. However, there can be no guarantee that the fund will achieve a high degree of correlation with the index. A number of factors may
affect the fund’s ability to achieve a high correlation with its index, including the degree to which the fund uses a sampling technique (or otherwise gives a different weighting to a security than the index does). The correlation between the
performance of the fund and its index may also diverge due to transaction costs, asset valuations, timing variances, and differences between the fund’s portfolio and the index resulting