Market crises and Basel capital requirements: Could Basel III have been different? Evidence from Portugal, Ireland, Greece and Spain (PIGS)

Basel III represents a crucial step in strengthening the capital rules underlying banking operations, aimed at reducing the probability and severity of a systemic crisis. Alongside two supplementary capital buffers, the Basel Committee of Banking Supervision imposed severe pressure on the Value-at-Risk based Internal Models Approach in order to increase. This is to increase the capital base by adding the stressed Value-at-Risk component in an effort to reduce reliance on internal models while keeping the Standardized Approach avenue open. However, even though those measures might appear theoretically correct, evidence gathered for long and short exposures in Portugal, Italy, Greece and Spain highlights several defects in Basel III. We emphasize that leptokurtic models, primarily those derived from Extreme Value Theory, should be enforced in the regulations given their superior performance in market crises, and that Basel II could have shielded against 2008 mayhem provided that heavy-tailed techniques had been employed.

► Evidence on exposures in Portugal, Italy, Greece and Spain shows defects in Basel III. ► Basel regulations should impose heavy-tailed models to estimate Value-at-Risk. ► Basel III Minimum Capital Requirement could be softened via leptokurtic models. ► Leptokurtic models would have prevented capital shortage even with Basel II. ► Standardized Approach motivates inaccuracy and must be urgently revised.