WASHINGTON—More lending companies are mining Facebook, Twitter and other social-media data to help determine a borrower's creditworthiness or identity, a trend that is raising concerns among consumer groups and regulators.

Lending companies—some of which are backed with venture funding from Google Ventures, the venture-capital arm of Google Inc., and Accel Partners, an early Facebook Inc. investor—are looking at potential problems such as whether applicants put the same job information on their loan application as they posted...