London Stock Exchange Group Plc is in exclusive talks to buy RussellInvestments Ltd., the indexing and fund-management unit of Northwestern Mutual Life Insurance Co., to expand its FTSE International Ltd. business.

“LSE confirms that, further to the announcement on May 13 2014, it has now entered into exclusive discussions,” the exchange operator said in a Regulatory News Service statement. The discussions continue and there is no certainty of a transaction, LSE said.

Russell Investments attracted interest from suitors including Blackstone Group LP and Bain Capital LLC, people with knowledge of the matter said in March. Northwestern Mutual said in January that it had begun to explore options, including a possible sale, for its majority stake in Russell. The business may fetch about $3 billion, according to two of the people, who asked not to be identified because the talks weren’t public.

While Russell consists of two businesses, Northwestern wants to keep it whole rather than split it up, two of the people said in March. LSE didn’t specify today or on May 13 whether it’s interested in all or part of the business.

Russell, founded in 1936 and based in Seattle, owns an index division that operates equity benchmarks such as the Russell 2000 Index and a money manager that has $257 billion in assets. The other large index providers, such as S&P Dow Jones Indices LLC, MSCI Inc. and FTSE, aren’t tied to an asset manager.

In December 2011, LSE bought the 50 percent of FTSE International that it didn’t already own from Pearson Plc for 450 million pounds ($757 million) in cash. LSE has trailed rivals such as Deutsche Boerse AG in providing derivatives to investors. Owning an index operator makes it easier to provide futures and options contracts based on different gauges.