Ona Lewis, who once managed a $6 billion long-only equity portfolio at Banc One Investment Management, is returning to investment management and plans to launch an emerging markets fund by September. She is hoping to raise $150 million.Lewis formed Evermore Towb Global Investment Management in March. Her flagship long/short equity strategy will deploy about 60% of its assets in mid- to large-cap companies in such emerging markets countries as Brazil, Chile, China, India, Indonesia, Malaysia, Mexico and Taiwan, among others. The remaining 40% will be invested in U.S. and Western European companies that are active in emerging markets. The firm, based in...