Citigroup, Bank of America and Wells Fargo - alongside a Chinese bank - have been slapped with higher capital requirements in the 2016 update of global regulators' system for determining systemically-important financial institutions.

The change means the four banks are required to have a higher capacity to absorb losses. Citi's was moved from 2% of its risk-weighted assets to 2.5%, meaning it is only the second bank to enter the Financial Stability Board's highest-risk category, alongside JP Morgan.