He previously held senior roles at Nomura Securities Co, the brokerage unit of Nomura Holdings Inc. After he left Nomura, Saito served as CEO of the Industrial Revitalization Corporation of Japan, a now-defunct state-backed turnaround fund that invested in troubled companies.
What is the relationship between 'Nomura Holdings' and 'Nomura Securities' in the context of the input sentence.
Options: stock exchange, subsidiary, publisher, creator