Limits on borrowing that make it difficult to earn an adequate return on equity encourage banks to load up on riskier, high-profit-margin loans – and requiring banks to hold more capital for supposedly riskier categories of assets exacerbates the problem. For example, under the internationally-agreed Basel Committee rules that were in place before the 2008 crash, capital requirements for business loans were five times higher than for mortgage-backed securities that had AA or AAA ratings.