ISSN 1008-2204
CN 11-3979/C

分数布朗运动下或有可转债定价模型

Pricing CoCos in Fractional Brownian Motion Environment

  • 摘要: 或有可转债是重要的自救债务工具。实证结果表明,在上交所交易的银行股票收益率序列普遍存在较弱的长程自相关性。假设标的银行的股票价格动态方程由分数布朗运动驱动,其中分数布朗运动的Hurst指数H满足1/2 < H < 1,用于刻画股价的长记忆性、分形性。再应用基于偏好的均衡定价方法与分数布朗运动的条件分布对或有可转债定价。基于障碍期权与远期合约的定价公式,推导得或有可转债的显式定价公式。结果表明,虽然标的股票收益率序列的长程自相关性较弱,但由于或有可转债期限较长,其对或有可转债股权关联部分的价值有着显著的影响。标的股票收益率序列的长程自相关性对障碍期权的影响不可忽略。

     

    Abstract: Contingent Convertible Bonds (CoCos) are an important type of bail-in debts. The empirical results show that the price changes of the banks' stocks in the Shanghai Stock Exchange do exhibit a long-range serial autocorrelation and persistence in following a trend. The stock price of the underlying bank is described by a stochastic differential equation driven by a fractional Brownian motion with the Hurst parameter H satisfying 1/2 < H < 1, which characterizes the serial autocorrelation indicating a memory and the fractal character of the price. The preference based equilibrium approach and the conditional distribution of the fractional Brownian motion are employed to price the CoCos. The explicit pricing formula for CoCos is derived through pricing barrier options and forwards. The results indicate that the long-range serial autocorrelation in price changes of the underlying stock has a significant influence on the values of the equity-related components of the CoCos since the maturity is usually large, though the autocorrelation is weak. The values of the barrier options are significantly affected by the long-range autocorrelation of the returns on the underlying stocks.

     

/

返回文章
返回