secondarymortgage.comTBA: To-Be-Announced
A standardized MBS trade where the specific pools to be delivered are assigned only a few days before settlement, governed by issuer, coupon, and settlement date.
TBA mechanics increase market liquidity by enabling bulk trading without specifying pools upfront—crucial for high-volume dealers and passive investors. The standardization allows buyers to transact based on coupon, settlement date, and issuer (Fannie, Freddie, or Ginnie), knowing the pools delivered will conform to strict agency eligibility rules. This eliminates negotiation delays and supports daily pricing transparency.
For investors, TBA reduces operational risk and counterparty complexity but introduces delivery risk—the possibility that newly assigned pools are less desirable (e.g., higher prepayment speed or lower coupon). Settlement terms include standard haircuts and buy-in rights if pools fail delivery standards, so buyers rely heavily on servicer reporting and agency compliance history to mitigate uncertainty.
TBA markets became dominant after agency standardization in the 1980s and now underpin most MBS trading volume. Pricing anomalies—like wide yield gaps between TBAs of identical coupon but different settlement dates—can reveal expectations about rate changes, volatility, or liquidity shifts. Understanding TBA mechanics is essential for anyone executing or hedging MBS positions.
