18. Fair Value Measurement of Financial Instruments (continued) There has been no change in valuation techniques for Level 2 and Level 3 fair value hierarchy classifications. The fair value of derivatives used for hedging in Level 2 has been based on quotes from market makers or alternative market participants supported by observable inputs. The most significant observable inputs are market interest rates, exchange rates and yields. The fair value of unlisted investments classified within Level 3 is determined using a discounted cash flow valuation technique. The significant unobservable inputs used are expected future growth rates and discount rates. Changing these unobservable inputs based on reasonable alternative assumptions would not significantly change the valuation of the investments. The fair value estimate of the put option over a non-controlling interest in the U.S.A. classified within Level 3 is determined using a discounted cash flow valuation technique and contains a number of unobservable inputs, including the expected fair value of the associated investment property at the expected time of exercise, the expected time of exercise itself and the discount rate used. The expected time of exercise is in 2023 and the discount rate used is 6.3% (31st December 2022: 6.3%). The investment property’s fair value at the expected time of exercise is itself subject to a number of unobservable inputs which are similar to the inputs for the Group’s other completed investment properties, including the expected fair market rent and the expected capitalisation rate. If the investment property’s expected fair value at the time of exercise is higher, the fair value of the put option would also be higher at 30th June 2023. If the expected time of exercise is later or if the discount rate is higher, the fair value of the put option would be lower. The opposite is true for an earlier time of exercise or a lower discount rate. (b) Fair values of financial assets and liabilities carried at other than fair value The carrying amounts of the Group’s financial assets and liabilities carried at amortised cost are not materially different from their fair values at 30th June 2023 and 31st December 2022 except for the following financial liabilities, for which their carrying amounts and fair values are disclosed below: 30th June 2023 31st December 2022 Carrying amount Fair value Carrying amount Fair value HK$M HK$M HK$M HK$M Long-term loans and bonds 33,108 32,281 22,835 21,910 71