Members of BancAlliance, a consortium of about 200 community banks, will start using Lending Club, a website that facilitates loans to individuals, to build new portfolios of consumer loans. The banks will each commit to buy a certain amount of loans from Lending Club, which will vet borrowers for their ability to repay. Until now, small banks generally haven’t been able to justify the cost of underwriting unsecured loans of less than $35,000 without requiring collateral because big banks can do so much more efficiently. By relying on Lending Club’s software to quickly evaluate a borrower’s ability to repay, small banks hope to extend credit to borrowers with lower credit scores than they previously served and build a pool of those loans big enough that a few bad apples won’t bring down the whole portfolio.