“…Andreou & Ghysels (2002), among others, have argued that financial returns are known to exhibit sudden jumps in their volatility, a phenomenon caused essentially by structural breaks, and cannot be captured by regime-invariant parameters such as the single-state GARCH-type models. Abdymomunov (2013) and Augustyniak (2014) have confirmed that the volatility is indeed subject to two regimes: high and low (or normal), where the high risk regime is considered as a financial stress and closely related to periods of crisis. Alternatively, Hillebrand (2005) has affirmed that the nearly integrated behavior, generally observed in classical GARCH models, is the consequence of structural changes.…”