NewStar Financial Inc. (NEWS), the lender backed by private-equity firms Corsair Capital LLC and Capital Z Partners Management LLC, is extending its sale process into 2014, three people familiar with the matter said. The lender, which had asked suitors to submit initial offers by Nov. 8, is waiting until U.S. banks finish government-mandated stress-test evaluations of their balance sheets before soliciting another round of bids, said one of the people, who asked not to be identified because the process isn't public. Capital One Financial Corp. (COF), one of 30 U.S. banks that have to undergo the annual Fed exam, expressed interest in buying Boston-based NewStar, one person said. Banks with at least $50 billion in assets have until Jan. 6 to submit a capital plan to regulators, who announce the results in March. NewStar is working with Zurich-based Credit Suisse Group AG as an adviser on its potential sale, the people said.