This paper focuses on the task of detecting local episodes involving violation of the standard Itô semimartingale assumption for financial asset prices in real time that might induce arbitrage opportunities. Our proposed detectors, defined as stopping rules, are applied sequentially to...

We develop a test for mean stationarity of latent volatility curves using high-frequency data. To derive the asymptotic test size and power, we establish a functional invariance principle for semimartingales under a strong mixing condition. The power properties are analyzed under alternatives...

We develop a test for deciding whether the linear spaces spanned by the factor exposures of a large cross-section of assets toward latent systematic risk factors at two distinct points in time are the same. The test uses a panel of asset returns in local windows around the two time points. The...

We develop a test for deciding whether the linear spaces spanned by the factor exposures of a large cross-section of assets toward latent systematic risk factors at two distinct points in time are the same. The test uses a panel of asset returns in local windows around the two time points. The...

We develop a test for stationarity of latent volatility curves over time using high-frequency financial data. For deriving the asymptotic size and power of the test, we establish a functional invariance principle for semimartingales under a strong mixing condition. The power properties of our...

We propose model-free (nonparametric) estimators of the volatility of volatility and leverage effect using high-frequency observations of short-dated options. At each point in time, we integrate available options into estimates of the conditional characteristic function of the price increment...

We derive a nonparametric higher-order asymptotic expansion for small-time changes of conditional characteristic functions of Itô semimartingale increments. The asymptotics setup is of joint type: both the length of the time interval of the increment of the underlying process and the time gap...

This paper focuses on the task of detecting local episodes involving violation of the standard It\^o semimartingale assumption for financial asset prices in real time that might induce arbitrage opportunities. Our proposed detectors, defined as stopping rules, are applied sequentially to...

We develop a test for deciding whether the linear spaces spanned by the factor exposures of a large cross-section of assets towards latent systematic risk factors at two distinct points in time are the same. The test uses a panel of asset returns, with both the number of assets and the number of...