Russell Investments, the investment management firm and index provider for some of the world’s largest exchange traded funds, is reportedly drawing interest as a takeover target from private equity firms Blackstone (NYSE: BX) and Bain Capital.

Russell, a unit of Northwestern Mutual, could be worth $3 billion in a sale, report Matthew Monks, Matthew Leising and David Carey for Bloomberg. The news agency reported that Goldman Sachs (NYSE: GS) is looking for buyers for Russell and that Bain and Blackstone are among the possible suitors.

In January, it was reported that Northwestern Mutual was mulling a sale of Russell. Although not mentioned in connection with Russell, it has also been reported that Nasdaq OMX Group (NasdaqGM: NDAQ) and S&P Dow Jones Indices are shopping for acquisitions to bolster their index offerings. [Nasdaq, S&P Hunt for Index Acquisitions]

The list of ETFs that track Russell indices is extensive with indices constructed by the firm used by ETF sponsors such as BlackRock’s (NYSE: BLK) iShares, State Street Global Advisors, Vanguard, ProShars and Direxion.

Well-known ETFs tracking Russell indices include the iShares Russell 2000 ETF (NYSEArca: IWM), iShares Russell 1000 Growth ETF (NYSEArca: IWF) and the iShares Microcap ETF (NYSEArca: IWC).