A. Security Valuation: Securities are valued as of the close of trading on the New York Stock Exchange (generally 4 p.m., Eastern time) on the valuation date. Bonds and other temporary cash investments are valued using the latest bid prices or using valuations based on a matrix system (which considers such factors as security prices, yields, maturities, and ratings), both as furnished by independent pricing services. Structured debt securities, including mortgages and asset-backed securities, are valued using the latest bid prices or using valuations based on a matrix system that considers such factors as issuer, tranche, nominal or option-adjusted spreads, weighted average coupon, weighted average maturity, credit enhancements, and collateral, as furnished by independent pricing services. Investments in Vanguard Market Liquidity Fund are valued at that fund's net asset value.
Securities for which market quotations are not readily available, or whose values have been affected by events occurring before the fund's pricing time but after the close of the securities’ primary markets, are valued by methods deemed by the valuation designee to represent fair value and subject to oversight by the board of trustees.
B. Foreign Currency: Securities and other assets and liabilities denominated in foreign currencies are translated into U.S. dollars using exchange rates obtained from an independent third party as of the fund’s pricing time on the valuation date. Realized gains (losses) and unrealized appreciation (depreciation) on investment securities include the effects of changes in exchange rates since the securities were purchased, combined with the effects of changes in security prices. Fluctuations in the value of other assets and liabilities resulting from changes in exchange rates are recorded as unrealized foreign currency gains (losses) until the assets or liabilities are settled in cash, at which time they are recorded as realized foreign currency gains (losses).
C. Floating Rate Loan Interests: Floating rate loan interests represent interests in amounts owed by corporate or other borrowers. These instruments may be in the form of loans, trade claims or other receivables and may include standby financing commitments such as revolving credit facilities that obligate the fund to supply additional cash to the borrower on demand. Floating rate loan interests may be made directly with a borrower or acquired through assignment or participation. The fund's right to enforce a borrower’s compliance with the terms of the loan agreement, or benefit directly from the collateral supporting the loan, varies when the loan is a direct borrowing, an assignment, or a participation. Floating rate loan interests involve various risks including risk of loss in case of default, insolvency, or the bankruptcy of the borrower and are generally subject to restrictions on transfer with limited opportunities to sell them in secondary markets. The fund may also invest in loan commitments, which are contractual obligations for a future funding. The fund may earn a commitment fee on any unfunded portion of these commitments which is amortized to interest income over the commitment period. Both the funded portion of a floating rate loan interest as well as its unfunded commitment, if any, is reflected on the Schedule of Investments.
D. Futures Contracts: The fund uses futures contracts to invest in fixed income asset classes with greater efficiency and lower cost than is possible through direct investment, to add value when these instruments are attractively priced, or to adjust sensitivity to changes in interest rates. The primary risks associated with the use of futures contracts are imperfect correlation between changes in market values of bonds held by the fund and the prices of futures contracts, and the possibility of an illiquid market. Counterparty risk involving futures is mitigated because a regulated clearinghouse is the counterparty instead of the clearing broker. To further mitigate counterparty risk, the fund trades futures contracts on an exchange, monitors the financial strength of its clearing brokers and clearinghouse, and has entered into clearing agreements with its clearing brokers. The clearinghouse imposes initial margin requirements to secure the fund’s performance and requires daily settlement of variation margin representing changes in the market value of each contract. Any securities pledged as initial margin for open contracts are noted in the Schedule of Investments.
Futures contracts are valued at their quoted daily settlement prices. Fluctuations in the value of the contracts are recorded as an asset (liability).
E. Forward Currency Contracts: The fund enters into forward currency contracts to protect the value of securities and related receivables and payables against changes in future foreign exchange rates. Risks associated with these types of forward currency contracts include movement in the values of the foreign currencies relative to the U.S. dollar and the ability of the counterparties to fulfill their obligations under the contracts. The fund mitigates its counterparty risk by entering into forward currency contracts only with a diverse group of prequalified counterparties, monitoring their financial strength, entering into master netting arrangements with its counterparties, and requiring its counterparties to transfer collateral as security for their performance. In the absence of a default, the collateral pledged or received by the fund cannot be repledged, resold, or rehypothecated. The master netting arrangements provide that, in the event of a counterparty’s default (including bankruptcy), the fund may terminate the forward currency contracts, determine the net amount owed by either party in accordance with its master netting arrangements, and sell or retain any collateral held up to the net amount owed to the fund under the master netting arrangements. The forward currency contracts contain provisions whereby a counterparty may terminate open contracts if the fund’s net assets decline below a certain level, triggering a payment by the fund if the fund is in a net liability position at the time of the termination. The payment amount would be reduced by any collateral the fund has pledged. Any securities pledged as collateral for open contracts are noted in the Schedule of Investments. The value of collateral received or pledged is compared daily to the value of the forward currency contracts exposure with each counterparty, and any difference, if in excess of a specified minimum transfer amount, is adjusted and settled within two business days.
Forward currency contracts are valued at their quoted daily prices obtained from an independent third party, adjusted for currency risk based on the expiration date of each contract. Fluctuations in the value of the contracts are recorded as an asset (liability).
F. Swap Contracts: The fund invests in credit default swaps to adjust the overall credit risk of the fund or to actively overweight or underweight credit risk to a specific issuer or group of issuers. The fund may sell credit protection through credit default swaps to simulate investments in long positions that are either unavailable or considered to be less attractively priced in the bond market. The fund may purchase credit protection through credit default swaps to reduce credit exposure to a given issuer or issuers. Under the terms of the swaps, an up-front payment may be exchanged between the seller and buyer. In addition, the seller of the credit protection receives a periodic payment of premium from the buyer that is a fixed percentage applied to a notional amount. If, for example, the reference entity is subject to a credit event (such as bankruptcy, failure to pay, or obligation acceleration) during the term of the swap, the seller agrees to either physically settle or cash settle the swap contract. If the swap is physically settled, the seller agrees to pay the buyer an amount equal to the notional amount and take delivery of a debt instrument of the reference issuer with a par amount equal to such notional amount. If the swap is cash settled, the seller agrees to pay the buyer the difference between the notional amount and the final price for the relevant debt instrument, as determined either in a market auction or pursuant to a pre-agreed-upon valuation procedure.
