4.6.9 Portfolio hedging ...................................................................................................... 162 4.6.9.1 Fair value portfolio hedges ............................................................................... 162 4.6.9.1.1 Portfolio layer (formerly last-of-layer) hedges and other considerations (updated September 2023) .............................................. 165 4.6.9.2 Cash flow portfolio hedges (updated July 2024) ............................................... 165 4.6.10 Firm commitments that contain a foreign-currency-denominated fixed price ................ 168 4.6.11 Other exclusions ....................................................................................................... 169 4.7 Preexisting hedging relationships under ASC 815 ................................................................ 171 4.8 Hedge effectiveness ........................................................................................................... 171 4.8.1 What is 'highly effective'?.......................................................................................... 172 4.8.1.1 Over what period does the hedge have to be highly effective?