Second, some assets can't be converted into a form suitable for secured borrowing.

BBC: Business

As you would expect, in stressed parts of the eurozone the growth in secured borrowing has been exceptionally rapid: between 2005 and 2011, the ratio of encumbered assets to total assets increased tenfold for Greek banks, to one third of the total.

BBC: Business

Banks have become increasingly dependent on various forms of secured borrowing, especially in what's known as the repo market, which is where banks swap bonds and other assets for loans from hedge funds and specialist parts of banks (yes there are banks at both ends of this market).

BBC: Business