An International Monetary Fund paper published on Tuesday says asset-price bubbles are generated by a lack of high-yield assets relative to low-yield ones.

Stefano Giglio and Tiago Severo, the paper's authors, use an overlapping generations model with financial frictions and accumulation of both physical and intangible capital to examine whether capital accumulation in developed countries induced a shortage of high-yield financial assets and a surplus of low-yield securities in capital markets.