Refers to investment trusts which are populated by corporate bonds. In October 2001, Morgan Stanley's Tradable Custodial Receipts (Tracers) was launched. Tracers contain a number of coporate bonds and credit default swaps which are selected for liquidity and diversity. Lehman Brothers launched a similar product, Targeted Return Index Securities (Trains) in January 2002. Both contain investment grade bonds. If a bond falls out of the investment grade category, it is either liquidated from the trust or delivered to the investor. Both Tracers and Trains are 144a trust structures and are only available to qualified buyers because they are considered private securities due to the trust structure.