The third-largest U.S. owner of SFR homes is looking into selling most of its portfolio. : (Bloomberg)—Pretium Partners LLC, the third-largest owner of U.S. single-family rentals, is working with Morgan Stanley and Ardea Partners to explore options that could include a sale of most of the company’s homes, according to people with knowledge of the matter. Pretium, founded by former Goldman Sachs Group Inc. partner Donald Mullen, is considering ways to provide liquidity to early investors, said some of the people, who asked not be identified because the discussions are private.