Forecasting-volatility models typically rely on either daily or high frequency (HF) data and the choice between these two categories is not obvious. In particular, the latter allows to treat volatility as observable but they suffer of many limitations. HF data feature microstructure problem,...

The Efficiency Market Hypotheses (EMH) imply rational investors and no asset mispricing in the medium run. This paper critically evaluates on the point of whether an asset price bubble is an irrational phenomenon that cannot be detected. Thereby, I review the existing literature and reflect on...

We develop a penalized two-pass regression with time-varying factor loadings. The penalization in the first pass enforces sparsity for the time-variation drivers while also maintaining compatibility with the no arbitrage restrictions by regularizing appropriate groups of coefficients. The second...