From the Key Takeaways: " Banks globally entered the Covid-19 [coronavirus disease 2019] crisis with roughly US$ 5 trillion of capital above their Pillar 1 regulatory requirements.  The amount of additional lending will depend on how hard banks' capital is hit by the crisis, on their willingness to use the buffers and on other policy support.  In an adverse stress scenario such as the savings and loan crisis, banks' usable buffers would decline to US$ 800 billion, which could support US$ 5 trillion of additional loans (6% of total loans outstanding). Yet in a severely adverse scenario, similar to the Great Financial Crisis, the corresponding figures would be only US$ 270 billion and US$ 1 trillion (1.3% of total loans)."
BIS Bulletin No. 11; Bank for International Settlements Bulletin No. 11
2020 Bank for International Settlements
Bank for International Settlements: https://www.bis.org/