(a) Definitions. For purposes of this subpart:

(1) Mortgage assets means, with respect to an Enterprise, the dollar amount equal to the sum of:

(i) The unpaid principal balance of its single-family mortgage exposures, including any single-family loans that secure MBS guaranteed by the Enterprise;

(ii) The unpaid principal balance of its multifamily mortgage exposures, including any multifamily mortgage exposures that secure MBS guaranteed by the Enterprise;

(iii) The carrying value of its MBS guaranteed by an Enterprise, MBS guaranteed by Ginnie Mae, PLS, and other securitization exposures (other than its retained CRT exposures); and

(iv) The exposure amount of any other mortgage assets.

(2) Residential mortgage debt outstanding means the dollar amount of mortgage debt outstanding secured by one- to four-family residences or multifamily residences that are located in the United States (and excluding any mortgage debt outstanding secured by commercial or farm properties).

(b) Amount. An Enterprise must calculate its stability capital buffer under this section on an annual basis by December 31 of each year. The stability capital buffer of an Enterprise is equal to:

(1) The ratio of:

(i) The mortgage assets of the Enterprise as of December 31 of the previous calendar year; to

(ii) The residential mortgage debt outstanding as of December 31 of the previous calendar year, as published by FHFA;

(2) Minus 0.05;

(3) Multiplied by 5;

(4) Divided by 100; and

(5) Multiplied by the adjusted total assets of the Enterprise, as of December 31 of the previous calendar year.

(c) Effective date of an adjusted stability capital buffer—(1) Increase in stability capital buffer. An increase in the stability capital buffer of an Enterprise under this section will take effect (i.e., be incorporated into the maximum payout ratio under table 1 to paragraph (b)(5) in § 1240.11) on January 1 of the year that is one full calendar year after the increased stability capital buffer was calculated, provided that where a stability capital buffer under paragraph (c)(2) of this section is calculated to be a decrease in the stability capital buffer from the previously calculated scheduled increase applicable on the same January 1, the decreased stability capital buffer under paragraph (c)(2) shall take effect.

(2) Decrease in stability capital buffer. A decrease in the stability capital buffer of an Enterprise will take effect (i.e., be incorporated into the maximum payout ratio under table 1 to paragraph (b)(5) in § 1240.11) on January 1 of the year immediately following the calendar year in which the decreased stability capital buffer was calculated.