1. Institutions shall use one of the methods set out in Subsection 3 to calculate risk-weighted exposure amounts in accordance with the following hierarchy:
(a) where the conditions set out in Article 258 are met, an institution shall use the SEC-IRBA in accordance with Articles 259 and 260;
(b) where the SEC-IRBA may not be used, an institution shall use the SEC-SA in accordance with Articles 261 and 262;
(c) where the SEC-SA may not be used, an institution shall use the SEC-ERBA in accordance with Articles 263 and 264 for rated positions or positions in respect of which an inferred rating may be used.
2. For rated positions or positions in respect of which an inferred rating may be used, an institution shall use the SEC-ERBA instead of the SEC-SA in each of the following cases:
(a) where the application of the SEC-SA would result in a risk weight higher than 25 % for positions qualifying as positions in an STS securitisation;
(b) where the application of the SEC-SA would result in a
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