Standard&Poor's Ratings Services assigned its 'AA' rating to Massachusetts Housing Finance Agency's (MassHousing) single-family housing revenue bonds (SFHRB), series 181 and 182. At the same time, Standard&Poor's affirmed its 'AA' long-term rating and underlying rating (SPUR) on the agency's outstanding bonds issued under its SFHRB resolution. The outlook is positive. The ratings reflect our opinion of the following strengths: The very strong asset quality of the single-family loan portfolio, including a growing proportion of mortgage-backed securities (MBS) guaranteed by Fannie Mae; Very strong minimum parity of 113% (net of loan losses), as demonstrated in economic stress scenario cash flows that reflect fully funded loss coverage at the 'AA' level; Consistent strengthening in the indenture's equity position