Testing the predictive ability of corridor implied volatility under GARCH models

YesThis paper studies the predictive ability of corridor implied volatility (CIV) measure. It is motivated by the fact that CIV is measured with better precision and reliability than the model-free implied volatility due to the lack of liquid options in the tails of the risk-neutral distribution. By adding CIV measures to the modified GARCH specifications, the out-of-sample predictive ability of CIV is measured by the forecast accuracy of conditional volatility. It finds that the narrowest CIV measure, covering about 10% of the RND, dominate the 1-day ahead conditional volatility forecasts regardless of the choice of GARCH models in high volatile period; as market moves to non volatile periods, the optimal width broadens. For multi-day ahead forecasts narrow and mid-range CIV measures are favoured in the full sample and high volatile period for all forecast horizons, depending on which loss functions are used; whereas in non turbulent markets, certain mid-range CIV measures are favoured, for rare instances, wide CIV measures dominate the performance. Regarding the comparisons between best performed CIV measures and two benchmark measures (market volatility index and at-the-money Black–Scholes implied volatility), it shows that under the EGARCH framework, none of the benchmark measures are found to outperform best performed CIV measures, whereas under the GARCH and NAGARCH models, best performed CIV measures are outperformed by benchmark measures for certain instances

Yes, implied volatilities are not informationally efficient: an empirical estimate using options on interest rate futures contracts

The accuracy of volatility forecast estimators has been assessed using daily overlapping and non overlapping observations on two major short-term interest rate futures contracts traded in London. The use of a panelized data set has eliminated some of the drawbacks usually associated with non overlapping data estimation, such as the lack of accuracy due to an insufficient number of observations or the arbitrariness of the choice of tenor. In the same way non stationarity and long memory characteristics of daily overlapping time series are disposed of. Information content estimation in levels associated with the Hansen (1982) variance covariance matrix estimator provides reasonably accurate estimates, broadly similar to the corresponding benchmark panel data ones

A Quasi-analytical Interpolation Method for Pricing American Options under General Multi-dimensional Diffusion Processes

We present a quasi-analytical method for pricing multi-dimensional American options based on interpolating two arbitrage bounds, along the lines of Johnson (1983). Our method allows for the close examination of the interpolation parameter on a rigorous theoretical footing instead of empirical regression. The method can be adapted to general diffusion processes as long as quick and accurate pricing methods exist for the corresponding European and perpetual American options. The American option price is shown to be approximately equal to an interpolation of two European option prices with the interpolation weight proportional to a perpetual American option. In the Black-Scholes model, our method achieves the same e±ciency as Barone-Adesi and Whaley's (1987) quadratic approximation with our method being generally more accurate for out-of-the-money and long-maturity options. When applied to Heston's stochastic volatility model, our method is shown to be extremely e±cient and fairly accurate

Effect of transcranial direct current stimulation on neuroplasticity in corticomotor pathways of the tongue muscles

© 2017 John Wiley & Sons Ltd The aim of this study is to investigate effects of transcranial direct current stimulation (tDCS) on neuroplasticity in corticomotor pathways related to tongue muscles evoked by a training task using the tongue drive system (TDS). Using a crossover design, 13 healthy participants completed two sessions of tDCS while performing 30 min of TDS training. Sessions were spaced at least 2 weeks apart and participants randomly received anodal and sham tDCS stimulation in the first session and the other condition in the second session. Single and paired pulse transcranial magnetic stimulation was used to elicit motor evoked potentials (MEPs) of the tongue at three time-points: before, immediately after and 30 min after training. Participant-based reports of fun, pain, fatigue and motivation, level of difficulty and effort were evaluated on numerical rating scales. There was no consistent significant effect of anodal and sham stimulation on single or paired pulse stimulation MEP amplitude immediately or 30 min after TDS training. Irrespective of tDCS type, training with TDS induced cortical plasticity in terms of increased MEP amplitudes for higher stimulus intensities after 30 min compared with before and immediately after training. Participant-based reports revealed no significant difference between tDCS conditions for level of fun, fatigue, motivation, difficulty and level of effort but a significant increase in pain in the anodal condition, although pain level was low for both conditions. In conclusion, tongue MEP amplitudes appear to be sensitive to training with the tongue using TDS; however, anodal tDCS does not have an impact on training-evoked neuroplasticity of tongue corticomotor pathways

Cross-sectional analysis of risk-neutral skewness

The authors investigate the association of various firm-specific and marketwide factors with the risk-neutral skewness (RNS) implied by the prices of individual stock options. The analysis covers 149 U.S. firms over a four-year period. The authors find that, consistent with earlier studies, the RNS of individual firms varies significantly and negatively with firm size, firm systematic risk, and market volatility and varies significantly and positively with the RNS of the market index. The authors also find that most of the variation in individual RNS is explained by firm-specific rather than marketwide factors. The authors also document several interesting new results that are clearly unambiguous and significantly stronger than in earlier work, or opposite to earlier evidence, or for variables that have been examined for the first time. The results show that 1) market sentiment has a negative and significant effect on RNS; 2) the higher a firm’s own volatility, the more negative the RNS, a relationship that is in the same direction as for overall market volatility; 3) greater market liquidity is associated with more negative RNS, but the liquidity that is relevant for RNS is that of the options market, rather than that in the underlying stock. Surprisingly, volatility asymmetry is not relevant for RNS. Finally, the leverage ratio is not negatively but positively and strongly related with RNS