The two buyout firms that own Pharmaceutical Product Development LLC (PPD) are in advanced talks to sell some of their stakes in the U.S. clinical trials firm at a price that would value the entire company at more than $9 billion, including debt, people familiar with the matter said. The deal would see PPD’s owners, Carlyle Group LP and Hellman & Friedman LLC, continue to control the company jointly, the people said. Carlyle currently owns 60 percent of PPD and Hellman & Friedman owns 40 percent, with the two sharing governance rights.