Shares in U.K. housebuilders tumble following a Zoopla report showing agreed-upon home sales fell in June. This is as higher mortgage rates and political uncertainty slashed buyer demand by 15% on year. Compounding the sector's woes is a potential 4.5 billion-pound class-action lawsuit over alleged anticompetitive behavior, according to RBC Capital Markets. "The claim is difficult to prove, and we note that the CMA's recent investigation into housebuilders did not conclude that the Competition Act had been infringed," the analysts say. Persimmon shares are down 3.4%, Barratt Redrow trades 3% lower and Bellway shares fall 2.5%. (anthony.orunagoriainoff@dowjones.com)