This is reflected in the Basel III rules to be implemented in the coming years. Collateral is required when borrowing from central banks. It has been necessary to expand the collateral basis during the financial crisis. Uncollateralised lending in the money market, which was common prior to the crisis, has all but vanished in favour of collateralised lending.
The banks also need to pledge collateral when borrowing from central banks. All this has increased the need for collateral in banks. In many countries, collateral is restricted to government bonds. Denmark is unique in the sense that we have a very large and well-developed mortgage- credit sector and hence a large volume of outstanding mortgage bonds.