Affiliated Managers announces investment in EIG Global Energy Partners Affiliated Managers Grou is acquiring an equity interest in EIG Global Energy Partners. EIG’s management team continues to hold a majority of the equity in the company, and consistent with AMG’s partnership approach, will retain operating autonomy of the business. EIG also announced that William C. Sonneborn has been appointed President of EIG effective May 5. As part of the transaction, all of the senior professionals at EIG have agreed to long-term commitments to remain with the firm. The terms of the transaction were not disclosed, and the parties expect to complete the investment during the month of April.