TCW Group gained a long-term partner as a Nippon Life Insurance Co. investment enabled Carlyle Group LP to sell almost half of its stake in the $200 billion asset manager. After the deal closed on Wednesday, TCW’s managers control a plurality -- 44 percent -- of the firm as Nippon acquired 25 percent for about $490 million. Carlyle, which bought 60 percent of the company in February 2013, reduced its stake to 31 percent, moving the remaining holding to a long-term fund. The transaction values TCW at about 150 percent more than Carlyle’s initial investment, according to figures in an investor presentation.