Level from micro data on public operating REITs compiled by and purchased from SNL Financial. Level is calculated as the sum of Agency Securities (SNL variable 17992) from all mortgage REITs. Mortgage REITs are defined as investment companies with a Mortgage REIT, MBS REIT, or Specialty Finance REIT primary focus. Unadjusted flow is the change in the level; data for the most recent ten years show no significant seasonality.