THE BLACK SCHOLES FORMULA
THE BLACK SCHOLES FORMULA
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布莱克·斯科尔斯公式
DOI:
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发表时间:
2007
期刊:
影响因子:
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通讯作者:
Myron S. Scholes
中科院分区:
文献类型:
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作者:
Mark H.A. Davis;Myron S. Scholes
‘If options are correctly priced in the market, it should not be possible to make sure profits by creating portfolios of long and short positions in options and their underlying stocks. Using this principle, a theoretical valuation formula for options is derived.’ These are the first two sentences of the abstract of the great paper [2] by Fischer Black and Myron Scholes on option pricing, and encapsulate the basic idea, which is that—with the asset price model they employ—insisting on absence of arbitrage is enough to obtain a unique value for a call option on that asset. The resulting formula, (1.4) below, is the most famous formula in financial economics, and in fact that whole subject splits decisively into the pre-Black-Scholes and post-Black-Scholes eras. This article aims to give a self-contained derivation of the formula, some discussion of the hedge parameters, and some extensions of the formula, and to indicate why a formula based on a stylized mathematical model which is known not to be a particularly accurate representation of real asset prices has nevertheless proved so effective in the world of option trading. Section 1 formulates the model and states and proves the formula. As is well known, the formula can equally well be stated in the form of a partial differential equation (PDE); this is equation (1.5) below. Section 2 discusses the PDE aspects of Black-Scholes. Section 3 summarizes information about the option ‘Greeks’, while Sections 4 and 5 introduce what is actually a more useful form of Black-Scholes, usually known as the ‘Black formula’. Finally, Section 6 discusses the applications of the formula in market trading. We define the implied volatility and demonstrate a ‘robustness’ property of Black-Scholes which implies that effective hedging can be achieved even if the ‘true’ price process is substantially different from Black and Scholes’ stylized model.