This paper examines several US monthly financial time series data using fractional integration and cointegration techniques. The univariate analysis based on fractional integration aims to determine whether the series are I(1) (in which case markets might be efficient) or alternatively I(d) with...

This paper proposes a very general time series framework to capture the long-run behaviour of financial series. The suggested model includes linear and non-linear time trends, and stationary and nonstationary processes based on integer and/or fractional degrees of differentiation. Moreover, the...

This paper examines mean and volatility spillovers between four green municipal bonds issued by the US states of California, Colorado, Columbia and Ohio, and the role played by the recent Covid-19 pandemic and the COP policy announcements respectively. Specifically, four-variate VAR-GARCH-BEKK...