Structured Transactions and Megas

Review the sections below to view General Information, Legal Documents, and Data Collections for Megas, REMICs, Grantor Trusts, and SMBS.


Fannie Megas® (Megas) are single-class pass-through securities in which the underlying collateral are groups of existing Fannie Mae MBS or other Fannie Megas. The cash flows from the underlying MBS and/or Megas provide the cash flows for the Mega pool. The securities that back a Fannie Mega may be single-family or multifamily Fannie Mae MBS or previously issued Fannie Mega pools. Fannie Megas issued prior to Jan. 1, 2006, also may have been backed by Ginnie Mae securities.

Fannie Megas enable investors to accumulate pieces of similar, existing mortgage-backed securities to form a larger security with its own unique characteristics. Investors can consolidate small or paid-down pools in a Mega to help reduce administrative costs or form a Mega with certain characteristics, such as enhanced geographical diversity.

Additional data related to Megas can be located via the tools on the right and via additional links outlined below:

Legal Documents

Data Collections

As of July 2, 2018, the Mega links below will no longer be updated for Multifamily securities. DUS Disclose® will provide Multifamily Mega disclosures.

REMICs & Grantor Trusts

A Real Estate Mortgage Investment Conduit (REMIC) is a type of multiclass mortgage-related security in which interest and principal payments from the mortgage-related assets serving as collateral are structured into separately traded securities called classes.  The cash flow from the underlying collateral is directed to several classes, which may have different coupon rates, average lives, prepayment sensitivities, and final maturities.  REMICs further enhance the mortgage securities market with their increased efficiency.

A grantor trust is a pass-through vehicle that, like a REMIC, issues separately traded classes. However, grantor trusts are treated differently than REMICs for federal income tax purposes, and, unlike a REMIC, the classes in grantor trusts cannot be "time tranched." This means each grantor trust class must receive its proportionate share of principal from the underlying collateral each month until such collateral is paid off. Each holder of a grantor trust certificate is treated for tax purposes as owning an undivided interest in the underlying collateral. The mortgage-related assets serving as collateral and providing the cash flow for Fannie Mae grantor trusts are specifically described in the trust's disclosure documents.

Additional data related to REMICs can be located via the tools on the right and via additional links outlined below:

Legal Documents:

Data Collections


Stripped Mortgage-Backed Securities (SMBS) are pass-through securities that are created by separating — or stripping apart — the principal and interest payments from underlying mortgage assets that back standard mortgage-backed securities, REMIC certificates, previously issued SMBS certificates, or other mortgage-related assets. SMBS deals create one or more classes of securities:

  • Interest Only (IO) classes receive the interest cash flow from the underlying assets.
  • Principal Only (PO) classes receive the principal cash flow from the underlying assets.
  • Additional classes that may receive different portions of principal and interest.

Most SMBS can be recombined at a future date and are commonly identified by a trust number and class (e.g., SMBS Trust 318, and class 1 or 2).

Additional data related to SMBS can be located via the tools on the right and via additional links outlined below:

Legal Documents:

Data Collections


Fannie Mae guarantees to each Mega trust, REMIC trust, Structured Transaction Grantor Trust, and SMBS trust that it will supplement amounts received by the trust as required to permit timely payments of principal and interest on the certificates.


Page originally published: 12/21/11
Page last revised: 4/17/18

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