Insider-trading probe focuses on Medicare agency

The day Medicare officials began discussing whether to set new coverage limits on a costly new prostate-cancer treatment, the official in charge emailed three colleagues to put a "close hold" on the process. That meant: Keep quiet until an announcement later that month. Yet by the end of that same day, June 7, 2010, shares of the company that made the treatment, Dendreon Corp.,had plunged 10%. Before long, federal investigators took notice. The trading in Dendreon around that time is now at the center of one of three federal probes exploring whether employees of the Centers for Medicare and Medicaid Services, the agency that oversees billions in health spending, have leaked news that ended up in the hands of Wall Street traders, according to people with direct knowledge of the investigations.