Still, Democrats were quick to attack the latest nomination.

“Steve Mnuchin is just another Wall Street insider,” Senator Bernie Sanders of Vermont and Senator Elizabeth Warren of Massachusetts said in a joint statement. “That is not the type of change that Donald Trump promised to bring to Washington — that is hypocrisy at its worst.”

So far, none of the nominees who will be shaping economic policy have any significant experience in government.

Mr. Mnuchin, 53, and Mr. Ross, 79, are both familiar with buying distressed properties and selling for a profit. But they are political neophytes with scant experience in managing large organizations. They will oversee two government agencies that together employ about 130,000 people around the world.

In the case of Mr. Mnuchin at Treasury, his experience as a principal investor who made large sums of money through high-risk, high-return wagers suggests that he will look critically at the thicket of regulations that now constrain the risk-taking activities of investment banks.

That could mean a reassessment of what has come to be known as the Volcker Rule, part of the Dodd-Frank financial overhaul that followed the 2008 financial crisis. The rule forbids banks to make certain speculative investments with their own capital.

“I would say the No. 1 problem with the Volcker Rule is it’s too complicated and people don’t know how to interpret it,” Mr. Mnuchin said in an interview with CNBC on Wednesday. “So we’re going to look at what to do with it as we are with all of Dodd-Frank. The No. 1 priority is going to be to make sure that banks lend.”