TOKYO—Nikko Asset Management is to appoint its current chairman and former Nomura Holdings executive as its chief executive and president amid growing market expectations that Japan's No. 3 asset manager will go ahead with a long-awaited initial public offering this year.

Nikko Asset said Friday that Takumi Shibata, its current chairman, will succeed Charles Beazley, the chief executive, effective immediately, handing Shibata more power in shaping and implementing the firm's business strategy. Beazley will step down for personal reasons, the company said.