Nomura Holdings Inc. said it added 4.9 trillion yen ($52.5 billion) of retail assets in January, the biggest monthly gain in at least a decade, as individual investors purchased more stocks and mutual funds. Japan's biggest brokerage boosted total assets under management by 6.7 percent to 78.5 trillion yen as of Jan. 31 from a month earlier, Kenji Yamashita, a spokesman at Nomura in Tokyo, said in a phone interview. Retail assets are the highest since December 2007, when it managed 81.3 trillion yen, he said.