Papers by Christina Nikitopoulos-sklibosios
Social Science Research Network, 2022
Social Science Research Network, 2020
This study examines the role of daily volatility persistence in transmitting information from mac... more This study examines the role of daily volatility persistence in transmitting information from macro-economy in the volatility of energy markets. In crude oil and natural gas markets, macro-economic factors, such as the VIX, the credit spread and the Baltic exchange dirty index, impact volatility, and this impact is channeled via the volatility persistence. Further, the impact of returns and variances is primarily transmitted to volatility via the daily volatility persistence. The dependence of volatility persistence on market and macro-economic conditions is termed conditional volatility persistence (CVP). The variation in daily CVP is economically significant, contributing up to 17% of future volatility and accounting for 25% of the model's explanatory power. Inclusion of the CVP in the model significantly improves volatility forecasts. Based on the utility benefits of volatility forecasts, the CVP adjusted volatility models provide up to 160 bps benefit to investors compared to the HAR models, even after accounting for transaction costs and varying trading speeds.
Journal of Futures Markets, Jul 24, 2018
We empirically assess hedging interest rate risk beyond the conventional delta, gamma, and vega h... more We empirically assess hedging interest rate risk beyond the conventional delta, gamma, and vega hedges in long-dated crude oil options positions. Using factor hedging in a model featuring stochastic interest rates and stochastic volatility, interest rate hedges consistently provide an improvement beyond delta, gamma, and vega hedges. Under high interest rate volatility and/or when a rolling hedge is used, combining interest rate and delta hedging improves performance by up to four percentage points over the common hedges of gamma and/or vega. Thus, contrary to common practice, hedging interest rate risk should have priority over these "second-order" hedges.
Social Science Research Network, 2022
Journal of Commodity Markets, Sep 1, 2022
Journal of Banking and Finance, Oct 1, 2018
Does modelling stochastic interest rates, beyond stochastic volatility, improve pricing performan... more Does modelling stochastic interest rates, beyond stochastic volatility, improve pricing performance on long-dated commodity derivatives? To answer this question, we consider futures price models for commodity derivatives that allow for stochastic volatility and stochastic interest rates and a correlation structure between the underlying variables. We examine the empirical pricing performance of these models on pricing long-dated crude oil derivatives. Estimating the model parameters from historical crude oil futures prices and option prices, we find that stochastic interest rate models improve pricing performance on long-dated crude oil derivatives, when the interest rate volatility is relatively high. Furthermore, increasing the model dimensionality does not tend to improve the pricing performance on long-dated crude oil option prices, but it matters for long-dated futures prices. We also find empirical evidence for a negative correlation between crude oil futures prices and interest rates that contributes to improving fit to long-dated crude oil option prices.
RePEc: Research Papers in Economics, Feb 1, 2016
This paper considers the American option pricing problem under regime-switching by using the meth... more This paper considers the American option pricing problem under regime-switching by using the method-of-lines (MOL) scheme. American option prices in each regime involve prices in all other regimes. We treat the prices from other regimes implicitly, thus guaranteeing consistency. Iterative procedures are required but very few iterative steps are needed in practice. Numerical tests demonstrate the robustness, accuracy and efficiency of the proposed numerical scheme. We compare our results with Buffington and Elliott (2002)'s analytical approximation under two regimes. Our MOL scheme provides improved results especially for out-of-the money options, possibly because they use a separation of variable approach to the PDEs which cannot hold around the early exercise region. We also compare our results with those of Khaliq and Liu (2009) and suggest that their implicit scheme can be improved.
SSRN Electronic Journal, 2018
Jump risk plays an important role in current financial markets, yet it is a risk that cannot be e... more Jump risk plays an important role in current financial markets, yet it is a risk that cannot be easily measured and hedged. We numerically evaluate American call options under stochastic volatility, stochastic interest rates and jumps in both the asset price and volatility. By employing the Method of Lines (Meyer (2015)), the option price, the early exercise boundary and the Greeks are computed as part of the solution, which makes the numerical implementation time efficient. We conduct a numerical study to gauge the impact of jumps and stochastic interest rates on American call option prices and on their free boundaries. Jumps tend to increase the values of OTM and ATM options while decreasing the value of ITM options. The option delta is affected in a similar way. The impact of jumps on the free boundary is substantial and depends on the time to maturity. Near expiry, including asset jumps lowers the free boundary and the option holder is more likely to exercise the option, whilst including asset-volatility jumps elevates the free boundary and the option holder is less likely to exercise the option. This relation reverses at the beginning of the options life. The volatility, interest rates and their volatilities have a positive impact on the free boundaries and the option holder is less likely to exercise as these parameters increase.
Research Paper Series, 2019
This paper analyzes the importance of asset and volatility jumps in American option pricing model... more This paper analyzes the importance of asset and volatility jumps in American option pricing models. Using the Heston (1993) stochastic volatility model with asset and volatility jumps and the Hull and White (1987) short rate model, American options are numerically evaluated by the Method of Lines. The calibration of these models to S&P 100 American options data reveals that jumps, especially asset jumps, play an important role in improving the models’ ability to fit market data. Further, asset and volatility jumps tend to lift the free boundary, an effect that augments during volatile market conditions, while the additional volatility jumps marginally drift down the free boundary. As markets turn more volatile and exhibit jumps, American option holders become more prudent with their exercise decisions, especially as maturity of the options approaches.
Social Science Research Network, 2011
This paper proposes a framework for pricing credit derivatives within the defaultable Markovian H... more This paper proposes a framework for pricing credit derivatives within the defaultable Markovian HJM framework featuring unspanned stochastic volatility. Motivated by empirical evidence, hump-shaped level dependent stochastic volatility specifications are proposed, such that the model admits finite dimensional Markovian structures. The model also accommodates a correlation structure between the stochastic volatility, default-free interest rates and credit spreads. Defaultfree and defaultable bonds are explicitly priced and an approach for pricing credit default swaps and swaptions is presented where the credit swap rates can be approximated by defaultable bond prices with varying maturities. A sensitivity analysis capturing the impact of the model parameters including correlations and stochastic volatility, on the credit swap rate and the value of the credit swaption is also presented.
Social Science Research Network, 2010
This paper presents a class of defaultable term structure models within the HJM framework with st... more This paper presents a class of defaultable term structure models within the HJM framework with stochastic volatility. By modelling the connection between defaultfree and defaultable term structures, namely the credit spread, a correlation structure between the credit spread, the default-free interest rate and the stochastic volatility is also accommodated. Under certain volatility specifications, the model admits finite dimensional Markovian structures and consequently provides tractable solutions for default-free and defaultable bond prices. Furthermore, a bond pricing formula is obtained in terms of market observable quantities, specifically in terms of discrete tenor defaultable forward rates. The effect of stochastic volatility and of correlations between the stochastic volatility, defaultable short rate and credit spreads on the defaultable bond prices and returns is also investigated.
Social Science Research Network, 2016
This paper considers the American option pricing problem under regime-switching by using the meth... more This paper considers the American option pricing problem under regime-switching by using the method-of-lines (MOL) scheme. American option prices in each regime involve prices in all other regimes. We treat the prices from other regimes implicitly, thus guaranteeing consistency. Iterative procedures are required but very few iterative steps are needed in practice. Numerical tests demonstrate the robustness, accuracy and efficiency of the proposed numerical scheme. We compare our results with Buffington and Elliott (2002)'s analytical approximation under two regimes. Our MOL scheme provides improved results especially for out-of-the money options, possibly because they use a separation of variable approach to the PDEs which cannot hold around the early exercise region. We also compare our results with those of Khaliq and Liu (2009) and suggest that their implicit scheme can be improved.
Asia-pacific Financial Markets, Sep 1, 2003
This paper considers a class of term structure models that is a parameterisation of the Shirakawa... more This paper considers a class of term structure models that is a parameterisation of the Shirakawa (1991) extension of the Heath et al. (1992) model to the case of jump-diffusions. We consider specific forward rate volatility structures that incorporate state dependent Wiener volatility functions and time dependent Poisson volatility functions. Within this framework, we discuss the Markovianisation issue, and obtain the corresponding affine term structure of interest rates. As a result we are able to obtain a broad tractable class of jump-diffusion term structure models. We relate our approach to the existing class of jump-diffusion term structure models whose starting point is a jumpdiffusion process for the spot rate. In particular we obtain natural jump-diffusion versions of the Hull and White (1990, 1994) one-factor and two-factor models and the Ritchken and Sankarasubramanian (1995) model within the HJM framework. We also give some numerical simulations to gauge the effect of the jump-component on yield curves and the implications of various volatility specifications for the spot rate distribution.
Dynamic modeling and econometrics in economics and finance, 2015
The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.
Social Science Research Network, 2004
The defaultable forward rate is modeled as a jump diffusion process within the Schönbucher (2000,... more The defaultable forward rate is modeled as a jump diffusion process within the Schönbucher (2000, 2003) general Heath, Jarrow and Morton (1992) framework where jumps in the defaultable term structure f d (t, T) cause jumps and defaults to the defaultable bond prices P d (t, T). Within this framework, we investigate an appropriate forward rate volatility structure that results in Markovian defaultable spot rate dynamics. In particular, we consider state dependent Wiener volatility functions and time dependent Poisson volatility functions. The corresponding term structures of interest rates are expressed as finite dimensional affine realisations in terms of benchmark defaultable forward rates. In addition, we extend this model to incorporate stochastic spreads by allowing jump intensities to follow a square-root diffusion process. In that case the dynamics become non-Markovian and to restore path independence we propose either an approximate Markovian scheme or, alternatively, constant Poisson volatility functions. We also conduct some numerical simulations to gauge the effect of the stochastic intensity and the distributional implications of various volatility specifications.
Springer eBooks, 2015
The Partial Differential Equation (PDE) Approach is one of the techniques in solving the pricing ... more The Partial Differential Equation (PDE) Approach is one of the techniques in solving the pricing equations for financial instruments. The solution technique of the PDE approach is the Fourier transform, which reduces the problem of solving the PDE to one of solving an ordinary differential equation (ODE). The Fourier transform provides quite a general framework for solving the PDEs of financial instruments when the underlying asset follows a jump-diffusion process and also when we deal with American options. This chapter illustrates that in the case of geometric Brownian motion, the ODE determining the transform can be solved explicitly. It shows how the PDE approach is related to pricing derivatives in terms of integration and expectations under the risk-neutral measure.
Springer eBooks, 2015
We study an incomplete market model, based on jump-diffusion processes with parameters that are s... more We study an incomplete market model, based on jump-diffusion processes with parameters that are switched at random times. The set of equivalent martingale measures is determined. An analogue of the fundamental equation for the option price is derived. In the case of the two-state hidden Markov process we obtain explicit formulae for the option prices. Furthermore, we numerically compare the results corresponding to different equivalent martingale measures.
Dynamic modeling and econometrics in economics and finance, 2015
This chapter develops a continuous hedging argument for derivative security pricing. Following fa... more This chapter develops a continuous hedging argument for derivative security pricing. Following fairly closely the original Black and Scholes (1973) article, we make use of Ito’s lemma to derive the expression for the option value and exploit the idea of creating a hedged position by going long in one security, say the stock, and short in the other security, the option. Alternative hedging portfolios based on Merton’s approach and self financing strategy approach are also introduced.
Social Science Research Network, 2019
This paper analyzes the importance of asset and volatility jumps in American option pricing model... more This paper analyzes the importance of asset and volatility jumps in American option pricing models. Using the Heston (1993) stochastic volatility model with asset and volatility jumps and the Hull and White (1987) short rate model, American options are numerically evaluated by the Method of Lines. The calibration of these models to S&P 100 American options data reveals that jumps, especially asset jumps, play an important role in improving the models' ability to fit market data. Further, asset and volatility jumps tend to lift the free boundary, an effect that augments during volatile market conditions, while the additional volatility jumps marginally drift down the free boundary. As markets turn more volatile and exhibit jumps, American option holders become more prudent with their exercise decisions, especially as maturity of the options approaches.
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Papers by Christina Nikitopoulos-sklibosios