April 26 - Standard & Poor's Ratings Services today said it assigned its 'BBB-f' fund credit quality and 'S3' volatility ratings on the iShares Baa - Ba Rated Corporate Bond Fund and its 'B-f' fund credit quality and 'S5' volatility ratings on the iShares B - Ca Rated Corporate Bond Fund. The funds are among the more than 215 investment portfolios of the iShares Trust. The trust was organized as a Delaware statutory trust on Dec. 16, 1999, and is authorized to have multiple series or portfolios. The trust is an open-end management investment company registered under the Investment Company Act of 1940 as amended. The offering of the trust's shares is registered under the Securities Act of 1933 as amended. The shares of the trust are listed and traded at market prices on national securities exchanges. BlackRock Fund Advisors (BFA), the funds' investment adviser, is a subsidiary of BlackRock Inc. As of March 31, 2012, BlackRock Inc. and its affiliates provided investment advisory services for assets estimated at $3.684 trillion. State Street Bank & Trust Co. is the administrator, custodian, and transfer agent for the funds. BlackRock Investments LLC, a subsidiary of BlackRock Inc., is the funds' distributor. BFA uses a passive or indexing approach to achieve the funds' investment objectives. The funds, launched this week, seek investment results that correspond generally to the price and yield performance, before fees and expenses, of the corresponding underlying index. The underlying index for the iShares Baa - Ba Rated Corporate Bond Fund is the Barclays Capital U.S. Corporate Baa - Ba Capped Index, a subset of the Barclays U.S. Corporate Index and Barclays U.S. Corporate High Yield Index that measures the performance of the taxable Baa1 - Ba3 rated range of the fixed-rate U.S. dollar-denominated corporate bond market. The underlying index for the iShares B - Ca Rated Corporate Bond Fund is the Barclays Capital U.S. Corporate B - Ca Capped Index, a subset of the Barclays U.S. Corporate High Yield Index that measures the performance of the taxable B1 - Ca rated range of the fixed-rate U.S. dollar-denominated corporate bond market. Our fund credit quality ratings, identified by the 'f' subscript, reflect the level of protection the fund provides against losses from credit defaults. The credit quality ratings scale ranges from 'AAAf' (extremely strong protection against losses from credit defaults) to 'CCCf' (extremely vulnerable to losses from credit defaults). The ratings from 'AAf' to 'CCCf' may be modified by the addition of a plus (+) or minus (-) sign to show relative standing within the major rating categories. Our fund volatility ratings, identified by the 'S' scale, are based on our current opinion of a fixed-income fund's sensitivity to changing market conditions, relative to a portfolio made up of government securities and denominated in the base currency of the fund. The volatility ratings are based on a scale from 'S1' (lowest sensitivity) to 'S6' (highest sensitivity). Volatility ratings evaluate sensitivity to factors such as interest rate movements, credit risk, and liquidity. We will monitor the fund monthly to ensure the consistency of the credit and volatility profiles with the assigned ratings. RELATED CRITERIA AND RESEARCH -- Fund Credit Quality Rating Criteria, Feb. 2, 2007 -- Fund Volatility Rating Criteria, Feb. 2, 2007 Complete ratings information is available to subscribers of RatingsDirect on the Global Credit Portal at www.globalcreditportal.com. All ratings affected by this rating action can be found on Standard & Poor's public Web site at www.standardandpoors.com. Use the Ratings search box located in the left column.