Environmentally minded activists in October filed a complaint to the Principles for Responsible Investment (PRI), a London-based organization with some 5,300 signatories that aims to promote sustainable investment by money managers.

But a PRI spokesman said via email that after review of the complaint against TIAA and its Nuveen asset-management arm, the concerns "did not constitute an impediment to the signatory's ability to act in accordance with our six principles" and that no further action was taken.

The decision marks a win for TIAA and Nuveen, which like rivals face growing pressure from asset owners to consider environmental, social and governance (ESG) issues.

Investment activists who backed the complaint said they were disappointed by the decision and worry the PRI could provide public-relations cover for fund firms under pressure to leave responsible investing groups with stricter criteria, as Vanguard Group Inc did last week.

TIAA and Nuveen had some $78 billion invested in fossil fuels out of TIAA's total assets of $1.2 trillion, said the Oct. 19 complaint now signed by roughly 780 TIAA clients.

Filers said the coal infrastructure and other portfolio holdings of TIAA and Nuveen clashed with the views of TIAA's academic client base as universities move to divest from fossil fuels over their role in driving climate change.

The PRI, which rarely suspends members, asks signatories like Nuveen to commit to six principles, including incorporating environmental, social or governance (ESG) matters into decision-making and asking portfolio companies for more disclosures.

TIAA said in a statement that "Based on the U.N. PRI's decision we believe our responses and the supplemental materials we provided demonstrate our commitment to responsible investing, the thoughtful approach we take to incorporating ESG considerations into our investment processes and our dedication to transparency and engagement with the companies we invest in on behalf of our clients."

Hana Heineken, senior attorney at the Center for International Environmental Law, who helped draft the complaint, said the decision could allow managers to advertise a commitment to the environment without signing on to the more robust goals of other groups like the Net Zero Asset Managers initiative, which seeks net-zero emissions by 2050.

"If the PRI allows these weak standards we're seeing play out to persist, that means the PRI is enabling greenwashing," Heineken said. The term describes exaggerated and misleading claims that suggest a company or country are stewards of the environment without real action.

(Reporting by Ross Kerber in Boston; Editing by Matthew Lewis)

By Ross Kerber