Complex sentence: This insurance protects mortgage lenders against mortgage defaults on mortgages of less than 20% down, which makes it more economical for banks to lend to riskier borrowers because some of the risk will be borne by CMHC.
Split into simpler sentences: This insurance protects mortgage lenders against mortgage defaults on mortgages of less than 20% down. The insurance makes it more economical for banks to lend to riskier borrowers because some of the risk will be borne by CMHC.