The American Federation of Teachers union is taking on Third Point's Dan Loeb and other big hedge fund managers over pensions.
"What we said to Dan Loeb and other investment managers is that transparency counts," AFT President Randi Weingarten told CNBC on Wednesday.
She was echoing the sentiments of an AFT report titled "Ranking Asset Managers," in which the union wrote: "Many of the organizations attacking defined benefit [pension] plans are funded by hedge fund and private equity managers."
The AFT put together what it called an "Investment Manager Watch List." The union's list consisted of money managers who it claimed "contributed to, or sit on the governing board of, an organization that advocates for the replacement of defined benefit plans with defined contribution or cash balance plans."
(Related video: Pension crisis 'pretty scary' right now)
Weingarten—dubbed by Institutional Investor as the most powerful voice in the nationwide battle over pensions—explained the AFT's position during a "Squawk Box" appearance. "We want pension funds to know if you [money managers] ... are actually trying to kill pension funds."
In an interview at The New York Times' DealBook conference Tuesday, Loeb reacted to the AFT report, which was released in earlier this year. "Our investors disconnect politics from investing," he said.
"I put principles first before making money," he continued. "I'm very committed to ... individual rights and freedom."
(Read more: Loeb: I don't want to see FedEx CEO replaced)
Weingarten told CNBC on Wednesday that she wanted Loeb and other money managers soliciting business from defined benefit pension plans to disclose whether they support groups that "want to actually kill those same plans."