Mortgage fraud by lenders and borrowers increased enormously. Subprime loans have a higher risk of default than loans to prime borrowers. Borrowers having similar needs can form into a group of borrowers. Lenders offered more and more loans to higher-risk borrowers, including undocumented immigrants. Loan agreement governs relationship between the lenders and the borrowers. CRA loans are loans targeted to low and moderate income borrowers and neighborhoods. A bank aggregates the activities of many borrowers and lenders. The HOLC then refinanced the loans for the borrowers. Banks allow borrowers and lenders, of different sizes, to coordinate their activity. Extending crowdsourcing to unfamiliar lenders and borrowers opens up new opportunities. They also "undid the connection between borrowers and lenders". Banks implemented new strategies designed to cater to lower-income borrowers, including the adjustable-rate mortgage. Sovereign borrowers are the largest debt borrowers in many financial markets. Shadow banking institutions are typically intermediaries between investors and borrowers. The average loan size for US borrowers is $5,000.