The CEO of Japan's top investment bank, Nomura Holdings, has stepped down from his position in light of an insider trading scandal within the bank. Kenichi Watanabe's resignation along with that of his top lieutenant Takumi Shibata were confirmed Thursday morning. The two men had been at the helm the takeover of Asian and European assets of Lehman Brothers when the American firm went down, and their scandalous departure poses questions about the global economic plan they'd hedged. Nomura is expected to hold a news conference updating the public on its management structure this morning. The company had been conducting an internal investigation into acts of insider trading dating back to 2010. Nomura is expected to name securities head Koji Nagai as Watanabe's replacement.