The Bloomberg Barclays U.S. Aggregate Bond Index provides a measure of the performance of the U.S. dollar denominated investment grade bond market, which includes investment grade (must be Baa3/BBB- or higher using the middle rating of Moody's Investor Service, Inc., Standard & Poor's, and Fitch Inc.) government bonds, investment grade corporate bonds, mortgage pass through securities, commercial mortgage backed securities and asset backed securities that are publicly for sale in the United States. The securities in the U.S. Aggregate Index must have at least 1 year remaining to maturity and must have $250 million or more of outstanding face value. Asset backed securities must have a minimum deal size of $500 million and a minimum tranche size of $25 million. For commercial mortgage backed securities, the original aggregate transaction must have a minimum deal size of $500 million, and a minimum tranche size of $25 million; the aggregate outstanding transaction sizes must be at least $300 million to remain in the index. In addition, the securities must be U.S. dollar denominated, fixed rate, non convertible, and taxable. Certain types of securities, such as flower bonds, TINs, and state and local government series bonds are excluded from the U.S. Aggregate Index. Also excluded from the U.S. Aggregate Index are structured notes with embedded swaps or other special features, private placements, floating rate securities and Eurobonds. The U.S. Aggregate Index is market capitalization weighted and the securities in the Index are updated on the last business day of each month.