The collapse of Lehman Brothers in 2008 drove up risk premia and triggered panic in financial markets, weakening assets in the United States and elsewhere, and threatening to provoke a credit crunch. In order to avoid asset fire-sales – which would have led to the disorderly unraveling of private-sector balance sheets, possibly triggering a new “Great Depression” or even bringing down the eurozone – advanced countries’ central banks began to purchase risky assets and increase lending to financial institutions, thus expanding the money supply.