15  Additionally, some segments in the non-bank financial sector exhibit high levels of vulnerability, similar in fact to those witnessed before the crisis. The search for yield may have also fostered an increase in leverage among relatively risky firms. For example, in recent years there has been a dramatic increase at the global level in the volume of lowerrated investment-grade corporate bonds and in the issuance of leverage loans, many of which are distributed in the form of CLOs. Macroprudential policies are well-equipped to deal with some of these risks. Indeed, the evidence suggests that these policies have been effective in curving financial stability risks. However, most of the existing tools in this area apply only to banks. In a world in which the share of non-banks is increasing, we need to develop new macroprudential tools that can be used to prevent the build-up of systemic risks outside the perimeter of the banking sector. Conclusions  Let me conclude. We seem to be in a new economic context characterised by older and declining populations, radical technological innovations (but not necessarily much higher productivity growth), high debt and low interest rates. All this entails substantial challenges both for macroeconomic policies and for the financial sector. Central banks will need to redefine not only their strategy but also the toolbox to be used when the constraints on their interest rate policy become binding.
Specifically, the central scenario of the UN assumes that, in net terms, around 25 million people will come to Europe over the 2020-2050 period. Therefore, a back-of-the-envelope calculation shows that holding the working age population constant would require at least three times the net migration flow assumed in the baseline scenario. Put another way, if Europe were to offset the projected decrease in the working-age population by receiving more migrants, it would need a net influx of around 2.6 million people each year over the next 3 decades, roughly twice the net migration flow Europe has received in the recent past. We cannot overstate the challenges these magnitudes pose from an economic, social and political perspective. 3  It is worth stressing that population ageing has become a global phenomenon. A closer look at the cross-country evolution of the old-age dependency ratio, that is, the ratio of the over65s to the working-age population, is illustrative of this trend. While in 1950 no country in the world featured an old-age dependency ratio above 20%, nowadays 59 countries surpass this level, including all but one European country. In 2050, according to the UN Population Projections, the group of countries with an old-age dependency ratio above 20% will double to 118, comprising most nations in Europe, North America and Asia.