(Adds background about pressure on active managers)
BOSTON, Sept 21 (Reuters) - Invesco Ltd plans to buy MassMutual unit OppenheimerFunds, a Financial Times publication reported on Friday.
Invesco and MassMutual declined to comment on the report by Ignites, an FT mutual fund publication.
Invesco and other actively managed funds have faced considerable pressure since the financial crisis amid a seismic shift of money into passively managed index and exchange-traded funds. Invesco has been building out its stable of passive products, including the acquisition of Guggenheim Investments' ETF business.
At the end of June, Invesco's assets under management totaled $934 billion, up 32 percent from the year-earlier period. But during the quarter, investors withdrew $8 billion from Invesco funds.
Invesco shares are down 28 percent over the past 12 months, compared to the 17 percent advance on the S&P 500 Index.
New York-based OppenheimerFunds is known for its stable of municipal bond funds that have taken big bets on debt issued by Puerto Rico. (Reporting by Tim McLaughlin Editing by Phil Berlowitz)