A pool of collateral (underlying assets) which is created and held by a trustee holding legal title to the assets, directly or through an agent, for the benefit of the pool and the holders of the respective pass-through certificates/ pass-through securities. A pass-through security, also a pay-through security, is a pool of fixed-income securities backed by a package of underlying assets of similar features. In other words, a pass-through pool is unique and distinguished by features such as size, prepayment profile, and geographic concentration or dispersion.

Pass-through pools are the basis for creating mortgage-backed securities (e.g., mortgage-backed bonds) by putting together similar mortgage loans (in terms of credit quality, maturity, etc.) into a single security.

Investors in a pass-through pool receive a portion of every interest and principal payment (less any service charges), commensurate (on a pro rata basis) to an investor’s ownership share in the pool.