The Swiss Financial Market Supervisory Authority (Finma) and the Swiss National Bank (SNB) on Wednesday announced more stringent liquidity rules for the country's two biggest banks, UBS and Credit Suisse, both of which have assets worth several times the country's GDP.

The core element of the new rules is a stringent stress scenario, which covers a general crisis across financial markets coupled with a creditors' loss of trust in the bank. The new liquidity regulations require that the banks -