The emphasis is shifting as the Trump administration rethinks how the government regulates the private sector. Many of the changes are intended to ease the perceived burdens on corporations and other businesses — not a surprise considering that many of Mr. Trump’s cabinet members and senior advisers hail from Wall Street or previously ran large companies.

When it comes to oversight of the financial industry, early indications point to a softening approach.

Monetary penalties imposed by the three main entities that police Wall Street — the Commodity Futures Trading Commission, the Securities and Exchange Commission, and the Financial Industry Regulatory Authority — were down sharply in the first half of 2017 compared with similar stretches in previous years. That trend partly reflects the winding down of cases stemming from the financial crisis, but corporate defense lawyers and banking industry officials say they detect a more business-friendly environment in general.

The Commodity Futures Trading Commission, created by Congress in 1974 to oversee the frenzied trading of futures contracts, was considered a regulatory afterthought for decades. With 706 full-time employees, including 178 in its enforcement division, it is far smaller than other law enforcement agencies.

In the Bill Clinton administration, the Treasury Department blocked the commission’s efforts to more closely regulate complex financial instruments known as derivatives, whose popularity was exploding. A decade later, the ubiquity of derivatives intensified the financial crisis because so many financial institutions were exposed to one another through the instruments.

Out of the ashes of the financial crisis, though, the commission took on a newly prominent role.

The Dodd-Frank financial overhaul law placed sweeping new regulatory powers in the agency’s hands. And a push from the agency’s chairman at the time, Gary Gensler, to go after bigger, splashier cases led the commission to a yearslong investigation into the manipulation of a widely used interest-rate benchmark known as Libor. Some of the world’s largest banks spent years stiff-arming the agency before grudgingly agreeing to cooperate once it became clear that the regulator was making progress.

The Libor investigation eventually turned up evidence of widespread misconduct. More than a dozen international banks admitted wrongdoing and paid billions of dollars in penalties to the commission and other regulators in the United States and overseas.