# 12 CFR § 1240.43 - Simplified supervisory formula approach (SSFA).

(a) General requirements for the SSFA. To use the SSFA to determine the risk weight for a securitization exposure, an Enterprise must have data that enables it to assign accurately the parameters described in paragraph (b) of this section. Data used to assign the parameters described in paragraph (b) of this section must be the most currently available data; if the contracts governing the underlying exposures of the securitization require payments on a monthly or quarterly basis, the data used to assign the parameters described in paragraph (b) of this section must be no more than 91 calendar days old. An Enterprise that does not have the appropriate data to assign the parameters described in paragraph (b) of this section must assign a risk weight of 1,250 percent to the exposure.

(b) SSFA parameters. To calculate the risk weight for a securitization exposure using the SSFA, an Enterprise must have accurate information on the following five inputs to the SSFA calculation:

(1) KG is the weighted-average (with unpaid principal used as the weight for each exposure) adjusted total capital requirement of the underlying exposures calculated using this subpart. KG is expressed as a decimal value between zero and one (that is, an average risk weight of 100 percent represents a value of KG equal to 0.08).

(2) Parameter W is expressed as a decimal value between zero and one. Parameter W is the ratio of the sum of the dollar amounts of any underlying exposures of the securitization that meet any of the criteria as set forth in paragraphs (b)(2)(i) through (vi) of this section to the balance, measured in dollars, of underlying exposures:

(i) Ninety days or more past due;

(ii) Subject to a bankruptcy or insolvency proceeding;

(iii) In the process of foreclosure;

(iv) Held as real estate owned;

(v) Has contractually deferred payments for 90 days or more, other than principal or interest payments deferred on:

(A) Federally-guaranteed student loans, in accordance with the terms of those guarantee programs; or

(B) Consumer loans, including non-federally-guaranteed student loans, provided that such payments are deferred pursuant to provisions included in the contract at the time funds are disbursed that provide for period(s) of deferral that are not initiated based on changes in the creditworthiness of the borrower; or

(vi) Is in default.

(3) Parameter A is the attachment point for the exposure, which represents the threshold at which credit losses will first be allocated to the exposure. Except as provided in § 1240.42(g) for nth-to-default credit derivatives, parameter A equals the ratio of the current dollar amount of underlying exposures that are subordinated to the exposure of the Enterprise to the current dollar amount of underlying exposures. Any reserve account funded by the accumulated cash flows from the underlying exposures that is subordinated to the Enterprise's securitization exposure may be included in the calculation of parameter A to the extent that cash is present in the account. Parameter A is expressed as a decimal value between zero and one.

(4) Parameter D is the detachment point for the exposure, which represents the threshold at which credit losses of principal allocated to the exposure would result in a total loss of principal. Except as provided in § 1240.42(g) for nth-to-default credit derivatives, parameter D equals parameter A plus the ratio of the current dollar amount of the securitization exposures that are pari passu with the exposure (that is, have equal seniority with respect to credit risk) to the current dollar amount of the underlying exposures. Parameter D is expressed as a decimal value between zero and one.

(5) A supervisory calibration parameter, p, is equal to 0.5 for securitization exposures that are not resecuritization exposures and equal to 1.5 for resecuritization exposures (except p is equal to 0.5 for resecuritization exposures secured by MBS guaranteed by an Enterprise).

(c) Mechanics of the SSFA. KG and W are used to calculate KA, the augmented value of KG, which reflects the observed credit quality of the underlying exposures. KA is defined in paragraph (d) of this section. The values of parameters A and D, relative to KA determine the risk weight assigned to a securitization exposure as described in paragraph (d) of this section. The risk weight assigned to a securitization exposure, or portion of a securitization exposure, as appropriate, is the larger of the risk weight determined in accordance with this paragraph (c) or paragraph (d) of this section and a risk weight of 20 percent.

(1) When the detachment point, parameter D, for a securitization exposure is less than or equal to KA, the exposure must be assigned a risk weight of 1,250 percent.

(2) When the attachment point, parameter A, for a securitization exposure is greater than or equal to KA, the Enterprise must calculate the risk weight in accordance with paragraph (d) of this section.

(3) When A is less than KA and D is greater than KA, the risk weight is a weighted-average of 1,250 percent and 1,250 percent times KSSFA calculated in accordance with paragraph (d) of this section. For the purpose of this weighted-average calculation:

(i) The weight assigned to 1,250 percent equals

(ii) The weight assigned to 1,250 percent times KSSFA equals

(iii) The risk weight will be set equal to:

(d) SSFA equation.

(1) The Enterprise must define the following parameters:

e = 2.71828, the base of the natural logarithms.

(2) Then the Enterprise must calculate KSSFA according to the following equation:

(3) The risk weight for the exposure (expressed as a percent) is equal to KSSFA * 1,250.

(e) Limitations. Notwithstanding any other provision of this section, an Enterprise must assign a risk weight of not less than 20 percent to a securitization exposure.

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