THL is committing $100 million to Hightower to support the firm's expansion. : (Bloomberg) --Thomas H. Lee Partners agreed to buy a stake in HighTower, betting on a wealth-management company that has been expanding with the purchase of investment-advisory firms. The private equity firm is acquiring a "significant" piece of the Chicago-based company, which oversees about $50 billion in client assets, HighTower’s chief executive, Elliot Weissbluth, said Wednesday. HighTower was advised by JPMorgan Chase & Co. on the deal and Weissbluth declined to comment on the terms.