Nomura Holdings Inc., the Japanese brokerage that has cut hundreds of jobs overseas since April, is now embarking on a companywide review of spending in order to reduce operating costs further over the next three years. Under the plan, called the “Waterline Project,” Nomura will evaluate the cost-effectiveness of employees’ daily activities and of the bank’s operations to determine how much money can be saved by 2020, Chief Executive Officer Koji Nagai said in an interview in Tokyo.