Pricing Asian options with stochastic volatility

Abstract

In this paper, we generalize the recently developed dimension reduction technique of Vecer for pricing arithmetic average Asian options. The assumption of constant volatility in Vecer's method will be relaxed to the case that volatility is randomly fluctuating and is driven by a mean-reverting (or ergodic) process. We then use the fast mean-reverting stochastic volatility asymptotic analysis introduced by Fouque, Papanicolaou and Sircar to derive an approximation to the option price which takes into account the skew of the implied volatility surface. This approximation is obtained by solving a pair of one-dimensional partial differential equations.     

Option prices and stock market momentum: evidence from China

Option prices tend to be correlated to past stock market returns due to market imperfections. We unprecedentedly examine this issue on the SSE 50 ETF option in the Chinese derivatives market. To measure the price pressure in the options market, we construct an implied volatility spread based on pairs of the SSE 50 ETF option with identical expiration dates and strike prices. By regressing the implied volatility spread on past stock returns, we find that past stock returns exert a strong influence on the pricing of index options. Specifically, we find that SSE 50 ETF calls are significantly overvalued relative to SSE 50 ETF puts after stock price increases and the reverse is also true after the stock price decreases. Moreover, we validate the momentum effects in the underlying stock market to be responsible for the price pressure. These findings are both economically and statistically significant and have important implications.     

Revisiting the incentive effects of executive stock options

We develop a multiperiod framework to evaluate the incentive effects of executive stock options (ESOs). For a given increase in the grant-date firm stock price (and a concurrent increase in return volatility), the increment of total value at the vesting date acts as a proxy for the incentive effects of ESOs. If the option is attached to the existing contract without adjusting cash compensation, we suggest that a firm should not always fix the strike price to the grant-date stock price; instead, the strike price should vary with the length of the vesting period. We also show that, compared with at-the-money options, restricted stock generates greater incentives to increase stock prices in some scenarios, especially when equity-based awards are vested early. If the vesting period is long, the firm could grant options instead of restricted stock to maximize incentives.     

On the qualitative effect of volatility and duration on prices of Asian options

We show that under the Black–Scholes assumption the price of an arithmetic average Asian call option with fixed strike increases with the level of volatility. This statement is not trivial to prove and for other models in general wrong. In fact we demonstrate that in a simple binomial model no such relationship holds. Under the Black–Scholes assumption however, we give a proof based on the maximum principle for parabolic partial differential equations. Furthermore we show that an increase in the length of duration over which the average is sampled also increases the price of an arithmetic average Asian call option, if the discounting effect is taken out. To show this, we use the result on volatility and the fact that a reparametrization in time corresponds to a change in volatility in the Black–Scholes model. Both results are extremely important for the risk management and risk assessment of portfolios that include Asian options.     

Modeling stock pinning

This paper investigates the effect of hedging strategies on the so-called pinning effect, i.e. the tendency of stock's prices to close near the strike price of heavily traded options as the expiration date nears. In the paper we extend the analysis of Avellaneda and Lipkin, who propose an explanation of stock pinning in terms of delta hedging strategies for long option positions. We adopt a model introduced by Frey and Stremme and show that, under the original assumptions of the model, pinning is driven by two effects: a hedging-dependent drift term that pushes the stock price toward the strike price and a hedging-dependent volatility term that constrains the stock price near the strike as it approaches it. Finally, we show that pinning can be generated by simulating trading in a double auction market. Pinning in the microstructure model is consistent with the Frey and Stremme model when both discrete hedging and stochastic impact are taken into account.     

Finance, Politics, and the Accounting for Stock Options

The politics of option accounting crosses party lines, reflecting both the interests of the affected constituencies and the desire for power over standard setting. House Bill HR-3574, which mandates an assumption of zero stock price volatility, runs counter to the recently passed Financial Accounting Standards Board (FASB) rule requiring fair-value expensing of stock options. For any option issued at or out of the money, where strike prices are normally set, expense recognition is zero under this bill's mandated assumption.
Besides excessive use of stock options, the lack of a "final peace" in the option accounting war appears to have encouraged another questionable corporate practice. This article examines a sample of "six-and-one restructurings," exchanges of options in which expensing of re-priced (deep out-of-the-money) options can be avoided if employees wait at least six months and one day before receiving new options. The authors found that market-adjusted stock prices tend to decrease during the six-month period before the strike price is reset. This result provides one more reason why companies should be required to use fair-value option pricing models to expense options.     

Do Stock Prices and Volatility Jump? Reconciling Evidence from Spot and Option Prices

This paper examines the empirical performance of jump diffusion models of stock price dynamics from joint options and stock markets data. The paper introduces a model with discontinuous correlated jumps in stock prices and stock price volatility, and with state-dependent arrival intensity. We discuss how to perform likelihood-based inference based upon joint options/returns data and present estimates of risk premiums for jump and volatility risks. The paper finds that while complex jump specifications add little explanatory power in fitting options data, these models fare better in fitting options and returns data simultaneously.     

How do oil supply and demand shocks affect Asian stock markets?

This paper examines how oil market shocks affect Asian stock prices using the structural vector autoregression (VAR) approach. Global oil supply and demand shocks are disentangled using sign restrictions and elasticity bounds. Oil price increases are bad news only if the source is from oil-market-specific demand shifts. Northeast Asian stock markets are more resilient as investors’ expectation of continued economic growth outweighs the adverse effect of higher oil prices. Increased global economic activity also stimulates stock prices. Global oil shocks are more important in explaining variability in Asian stock returns compared with the United States, suggesting different dynamics in Asia.     

Cross-sectional tests of deterministic volatility functions

We study the cross-sectional performance of option pricing models in which the volatility of the underlying stock is a deterministic function of the stock price and time. For each date in our sample of FTSE 100 index option prices, we fit an implied binomial tree to the panel of all European style options with different strike prices and maturities and then examine how well this model prices a corresponding panel of American style options. We find that the implied binomial tree model performs no better than an ad-hoc procedure of smoothing Black–Scholes implied volatilities across strike prices and maturities. Our cross-sectional results complement the time-series findings of Dumas et al. [J. Finance 53 (1998) 2059].     

Ironing out the kinks in executive compensation: Linking incentive pay to average stock prices

Traditional stock option grant is the most common form of incentive pay in executive compensation. Applying a principal-agent analysis, we find this common practice suboptimal and firms are better off linking incentive pay to average stock prices. Among other benefits, averaging reduces volatility by about 42%, making the incentive pay more attractive to risk-averse executives. Holding the cost of the option grant to the firm constant, Asian stock options are more cost effective than traditional stock options and provide stronger incentives to increase stock price. More importantly, the improvement is achieved with little impact on the option grant’s risk incentives (after adjusting for option cost). Finally, averaging also improves the value and incentive effects of indexed stock options.     

Options with Constant Underlying Elasticity in Strikes

Closed-form solutions are derived and interpreted for European options, with stochastic strike prices, that maintain constant elasticity of the strike with respect to the price of the underlying asset. We refer to such options as CUES. CUES preserve the relative shares of exercise price risk for both the buyer and writer of the option, regardless of whether the price of the underlying asset moves up or down. The relevance of the CUES concept is established through applications in two distinct fields. First, it is established that CUES-like options are embedded in private equity investments. This concept is then used in a novel application to determine the equity share of a private company corresponding to a given level of investment. Secondly, the advantages that CUES would provide over traditional executive stock option grants are considered and it is shown that CUES can provide enhanced incentive-alignment without increasing options expense to the company. JEL Classification: G130     

A P.D.E. approach to Asian options: analytical and numerical evidence

We first derive a one-state-variable partial differential equation, easy to implement, which characterizes the price of a European type Asian option. This result is explained and related to previous literature. We then derive new results on the hedging of an Asian option and propose analytical and numerical analysis on the comparison between Asian and European options. Our methodology which applies to “fixed-strike” Asian options as well as to “floating-strike” Asian options completes and clarifies various results in the literature. In this paper we focus on “backward-starting” Asian options. Our approach is quite general however, and we explain how to adapt our main results to the case of “forward-starting” Asian options.     

Financial inverse problem and reconstruction of?infinitely divisible distributions with Gaussian component

We consider an inverse problem of partial integro-differential equations of market prices of call options with many maturities and strike prices for geometric Lévy processes. We show the well-posedness (reconstruction, uniqueness, and stability) of the inverse problem among the class of infinitely divisible distributions with analyticity.     

Uncertain strike lookback options pricing with floating interest rate

Review of Derivatives Research - Considering the floating interest rate and the uncertainty of the strike price, we derive the pricing formulas of lookback options including lookback call option...     

A market-induced mechanism for stock pinning

Abstract

We propose a model to describe stock pinning on option expiration dates. We argue that if the open interest on a particular contract is unusually large, delta-hedging in aggregate by floor market-makers can impact the stock price and drive it to the strike price of the option. We derive a stochastic differential equation for the stock price which has a singular drift that accounts for the price-impact of delta-hedging. According to this model, the stock price has a finite probability of pinning at a strike. We calculate analytically and numerically this probability in terms of the volatility of the stock, the time-to-maturity, the open interest for the option under consideration and a ‘price elasticity’ constant that models price impact.     

Options trading volume and stock price response to earnings announcements

We examine the effect of options trading volume on the stock price response to earnings announcements over the period 1996–2007. Contrary to previous studies, we find no significant difference in the immediate stock price response to earnings information announcements in samples split between firms with listed options and firms without listed options. However, within the sample of firms with listed options stratified by options volume, we find that higher options trading volume reduces the immediate stock price response to earnings announcements. This conforms with evidence that stock prices of high options trading volume firms have anticipated and pre-empted some earnings information in the pre-announcement period. We also find that higher abnormal options trading volume around earnings announcements hastens the stock price adjustment to earnings news and reduces post-earnings announcement drift.     

Option pricing in the presence of natural boundaries and a quadratic diffusion term

This paper uses a probabilistic change-of-numeraire technique to compute closed-form prices of European options to exchange one asset against another when the relative price of the underlying assets follows a diffusion process with natural boundaries and a quadratic diffusion coefficient. The paper shows in particular how to interpret the option price formula in terms of exercise probabilities which are calculated under the martingale measures associated with two specific numeraire portfolios. An application to the pricing of bond options and certain interest rate derivatives illustrates the main results.     

Valuing employee reload options under the time vesting requirement

Upon the exercise of an employee stock option, the embedded reload provision entitles the holder to receive additional units of new options from the employer. The number of units of new options received is equal to the number of shares tendered as payment of strike and the new strike is set at the prevailing stock price. The reload provision may be subject to a time vesting requirement, that is, after each exercise, the employee is prohibited from exercising the reload until the end of a vesting period. In this paper, we construct an efficient numerical algorithm that computes the market value of the employee reload options under a time vesting requirement. Also, we explore the analytic properties of the price functions and optimal exercise policies of the employee reload options.     

A reduced PDE method for European option pricing under multi-scale,multi-factor stochastic volatility

The number of tailor-made hybrid structured products has risen more prominently to fit each investor’s preferences and requirements as they become more diversified. The structured products entail synthetic derivatives such as combinations of bonds and/or stocks conditional on how they are backed up by underlying securities, stochastic volatility, stochastic interest rates or exchanges rates. The complexity of these multi-asset structures yields lots of difficulties of pricing the products. Because of the complexity, Monte-Carlo simulation is a possible choice to price them but it may not produce stable Greeks leading to a trouble in hedging against risks. In this light, it is desirable to use partial differential equations with relevant analytic and numerical techniques. Even if the partial differential equation method would generate stable security prices and Greeks for single asset options, however, it may result in the curse of dimensionality when pricing multi-asset derivatives. In this study, we make the best use of multi-scale nature of stochastic volatility to lift the curse of dimensionality for up to three asset cases. Also, we present a transformation formula by which the pricing group parameters required for the multi-asset options in illiquid market can be calculated from the underlying market parameters.