However, given the slow recovery of the global economy, central banks have kept their policy rates low for an extraordinarily long period and have resorted to unconventional means to provide additional stimulus. While these measures have raised asset prices, low interest rates pose a serious challenge for pension funds.5  4  Bank of Canada, Financial System Review, (December 2013): iii.
5  The Mercer Pension Health Index in Canada, which tracks the ratio of assets to liabilities for a model defined benefit pension plan, shows that the ratio fell to slightly more than 70 per cent in early 2009 and began rising in 2010 but fell below 80 per cent again in 2012.