根本就唔撚係咁解
Time value係講緊cost of money,
valued by risk-free rate,
係講緊你用錢個機會成本係highest valued option forgone, ie best alternative risk-free cash-equivalent investment
銀行個利率同risk-free rate無必然性,
本身銀行有一部分收入就係靠個spread離賺錢
最簡單的解釋就係明買明賣,
銀行要借錢比人,問存戶借,所以要比息,
存戶要搵地方存錢,覺得銀行最好,所以就擺低
再深入d 息就係market price, QD = QS equilibrium個位,
Determinant 就係相關銀行提供的risk/reward