A term used to describe a forward mortgage-backed securities trade. Pass-through securities issued by Freddie Mac, Fannie Mae and Ginnie Mae trade in the TBA market. The term TBA is derived from the fact that the actual mortgage-backed security that will be delivered to fulfill a TBA trade is not designated at the time the trade is made. The securities are "to be announced" 48 hours prior to the established trade settlement date. 

|||The settlement procedures of mortgage-backed securities TBA trades are established by the Bond Market Association. Each type of agency pass-through security is given a specific trade settlement date for each month. Trade counterparties are required to exchange pool information by 3:00 pm (EST) 48 hours prior to the established settlement date. Trades are allocated in $1 million lots.