Such capital add-ons do more than merely improve the resilience of a SIFI, in other words reduce its probability of failure. They surely are also a suitable instrument with which to put a price tag on the implicit guarantee that SIFIs are deemed to enjoy.
Formal decisions have yet to be taken as to the exact application modalities of the SIFI surcharge, especially its size. Nevertheless, I expect that at the end of the day the amount of additional capital required from a SIFI will be related to its systemic importance and will in all likelihood lie somewhere between two and three percent.