Asymmetric nexus between shadow economy and financial instability: Does institutional quality matter?

Policymakers worldwide, especially central banks, are concerned about the causes and remedies of financial instability. This study examines the asymmetric influence of the shadow economy on financial instability. Moreover, the study analyzes the moderating role of institutional quality (IQ) in the shadow economy and financial instability nexus. This study used novel econometric techniques, including RALS-ADF and RALS-LM unit root tests, RALS-Fourier ARDL, NARDL, and single Fourier-Toda and Yamamoto causality tests, using yearly data from 1984 to 2020 for Turkey. Specifically, a positive shock to IQ declines financial instability, while a negative shock to IQ promotes it. Further, the negative shock to SE lessens the financial instability. Moreover, the negative shock to the interaction term implies that the shadow economy outweighs the IQ (depending on the level of IQ) in its effect in the case of Turkey, i.e., even if IQ increases (which usually decreases financial instability), the increasing SE has a dominant effect, and eventually upsurges financial instability. Additionally, in line with the institutional failure hypothesis, the negative shock to interaction term leads to a substantial increase in financial instability. Finally, the findings showed a one-way causality that runs from economic growth to financial instability and bidirectional causality between SE and GDP. The government should reduce shadow economic activities in the economy by enhancing IQ, which can increase government revenue and reduce financial instability.