In the March 2012 rebalancing a significant number of bonds that were eligible for the index but were being excluded because of a technical error were added to the index. A measure of the average price change of all bonds in the index weighted by par amount. Individual bond prices are derived from the volume weighted average price of all trades reported by TRACE from the prior days trading. Prices calculated do not include accrued (clean price). FINRA - Bloomberg Active US Corporate Bond Indices are comprised of the active (most frequently traded) fixed coupon bonds represented by FINRA TRACE, FINRA's transaction reporting facility that disseminates all over-the-counter secondary market transactions in these public bonds. The indices are rebalanced on a monthly basis. Type NBBHTR MEMB for constituent information. Index launch date: October 17, 2005.