Donald Trump is 'banking' Paul Atkins, on a longtime critic of heavy regulation, to flesh out his new administration’s plans for remaking the financial rule book. Atkins, 58, is on the Trump Transition Team, charged with recommending policies on financial regulation, according to current and former regulators briefed on the matter. As a Republican SEC Commissioner from 2002 to 2008, Atkins, spoke out against large company fines and sweeping stock-trading requirements.

The fact that Mr. Trump has turned to Mr. Atkins for recommendations provides an additional window into how the president-elect is likely to govern. Mr. Atkins, too, has repeatedly assailed Dodd-Frank, targeting provisions such as the creation of a systemic-risk council that has the power to designate large financial firms for bank-like regulation from the Federal Reserve. Mr. Atkins has said the council will “substitute government judgments for investor judgments, deciding for investors whether a product merits investment.”

During his time at the SEC, Atkins was critical of the agency’s approach to cracking down on corporate misdeeds through large penalties against firms that agreed to settle fraud charges. While proponents argued that large financial penalties deter companies from engaging in illegal behavior, Mr. Atkins maintained they punish shareholders.

“Are we just sort of headline-grabbing?” he asked in a 2005 interview with Business Week. “Is that really the best way to deter bad conduct, by hurting the people that we’re supposedly helping? No. The best solution is to hold individuals accountable because someone in the company cooked the books.”

Atkins repeatedly criticized the scope of financial regulation, which he warned often came at the expense of market competition and could lead to unforeseen consequences.  Along with GOP Commissioner Cynthia Glassman, he dissented in 2005 from backing a sweeping package of stock-trading overhauls known as Regulation National Market System, or Reg NMS, warning its provisions were unnecessarily complex and could lead to unanticipated market distortions. The SEC approved the measure.

He also dissented from rules to regulate the murky world of hedge funds, arguing that the SEC lacked the authority and that no pretext existed for the requirements since fraud wasn’t rampant in the industry.

Since leaving the SEC in 2008, Mr. Atkins has served as CEO of Patomak Global Partners, a firm he founded that advises financial companies on compliance issues. The company employs a deep bench of former Republican officials, including its president, Dan Gallagher, and Kathleen Casey, both former SEC commissioners. And just last month, a federal judge named Mr. Atkins as an independent monitor of Deutsche Bank's systems for reporting trades in its giant derivatives book.