Walmart heir Christy Walton will co-host a fundraiser for U.S. Vice President Kamala Harris, signalling the Democratic candidate's growing popularity among wealthy donors and business leaders. Tickets range from $1,250 to $100,000 for a lunch reception to be held in Jackson Hole, Wyoming, on September 15, with Michigan Gov. Gretchen Whitmer and former Montana Gov. Steve Bullock in attendance, according to the invitation. Walton is listed as a co-host of the event,...