A Prospectuses Supplement filing for Vanguard Prime Money Market Fund and Vanguard Treasury Money Market Fund tells us about an, "Important Change to Vanguard Prime Money Market Fund and Vanguard Treasury Money Market Fund." It says, "Effective June 30, 2018, David R. Glocke will retire from The Vanguard Group, Inc., and will no longer serve as a portfolio manager for Vanguard Prime Money Market Fund or Vanguard Treasury Money Market Fund." It adds, "Nafis T. Smith, who currently serves as a portfolio manager with Mr. Glocke, will remain as the sole portfolio manager of the Funds upon Mr. Glocke's retirement. The Funds' investment objectives, strategies, and policies will remain unchanged." Vanguard is the second largest manager of money market funds with $310.7 billion in assets (as of 5/31/18).