C. John Wilder resigned as chairman and chief executive of TXU with the merger. He planned to leave with at least $277 million worth of stock, according to a TXU regulatory filing in July. DALLAS - TXU Corp., the biggest power generator in Texas, officially passed from public to private ownership Wednesday and got a new name as investors closed the $32 billion buyout. ADVERTISEMENT The new owners are investors led by private-equity firms Kohlberg Kravis Roberts & Co. and TPG, formerly Texas Pacific Group. TXU changed its name to Energy Future Holdings Corp. Donald L. Evans, former U.S. commerce...