One empirical argument that has been around for some time and that clearly contra- dicts equity market efficiency is that market prices seem too volatile to be optimal estimates of the present value of future discounted cash flows. Based on this, it is deduced that systematic pricing errors...

I study the effects of risk and ambiguity (Knightian uncertainty) on optimal portfolios and equilibrium asset prices when investors receive information that is difficult to link to fundamentals. I show that the desire of investors to hedge ambiguity leads to portfolio inertia and excess...

I study the effects of aversion to risk and ambiguity (uncertainty in the sense of Knight (1921)) on the value of the market portfolio when investors receive public information that they find difficult to link to fundamentals and hence treat as ambiguous. I show that small changes in public...

We build an equilibrium model to explain why stock return predictability concentrates in bad times. The key feature is that investors use different forecasting models, and hence assess uncertainty differently. As economic conditions deteriorate, uncertainty rises and investors' opinions...

In this study, we apply a rolling window approach to wavelet-filtered (denoised) S&P500 returns (2000–2020) to obtain time varying Hurst exponents. We analyse the dynamics of the Hurst exponents by applying statistical tests (e.g., for stationarity, Gaussianity and self-similarity), a...

I perform textual analysis on high frequency (intraday) news articles. Selected articles are related to Euro-zone periphery crisis-affected countries (Portugal, Ireland, Italy, Greece, Spain). News pessimism affects stock returns negatively and volatility positively. Media pessimism does not...

We quantify the reaction of U.S. equity, bond futures, and exchange rate returns to oil price shocks driven by oil inventory news. Across most sectors, equity prices decrease in response to higher oil prices before the 2007/08 crisis but increase after it. Positive oil price shocks cause a...

The profitability of a trading system based on the momentum-like effects of price jumps was tested on the time series of 7 assets (EUR/USD, GBP/USD, USD/CHF and USD/JPY exchange rates and Light Crude Oil, E-Mini S&P 500 and VIX Futures), in each case for 7 different frequencies (ranging from...

The joint-hypothesis problem casts doubt on the results of market efficiency research. Specifically, it is hard to assess to what extent financial markets reflect economic fundamentals or mispricing. To address this issue, we study price formation in a large virtual asset market where...