Japanese investment bank Nomura is planning to double its New York-based prime brokerage team, as a number of new and expanding prime service firms look to pick up fresh US business in 2010.Nomura started its first US prime brokerage office in 2009, with a staff transplanted from Europe. The headcount now stands at 19, but the bank is believed to have plans to increase this to 40 by the end of 2010, as it builds out the business’s capabilities in stages.