The Department of Defense took a $400 million stake in MP Materials, loaning the company an additional $150 million to expand operations at its mining site in Mountain Pass, California. The deal was part of more than $2 billion in equity investments and loans the Pentagon has doled out to battery storage and mining companies during the second Trump administration to break Chinese dominance of critical minerals supply chains.

At the center of the deal was Alan Waldenberg, then head of the tax group at Schulte Roth & Zabel LLP, which later merged to form Mc Dermott Will & Schulte. Waldenberg's top client for three decades has been Cerberus Capital Management, whose founder, Stephen Feinberg, is now the number two civilian official at the Department of Defense. Waldenberg also manages Feinberg's irrevocable trust and served as president of his charitable foundation.

Waldenberg confirmed he represented the DOD in the MP Materials deal while simultaneously serving as outside counsel to Cerberus and Feinberg. He said Feinberg chose him due to a high degree of trust and that his involvement was discussed with DOD ethics staff. Richard Painter, former White House ethics lawyer under George W. Bush, questioned whether Feinberg should make decisions about hiring his personal lawyer.