A trust agreement is a legally binding bond agreement entered into between a bond issuer and a trustee to protect the interests of the bond holder.
The trust agreement describes the characteristics of the bond and the conditions for its withdrawal. It also specifies the amount of additional debt that the issuer may incur, as well as the circumstances and procedures in the event of an issuer default.
Most corporate bond issues over $5 million must include a trust deed and file a copy with the SEC.