The Wall Street lawyer Walter J. Clayton does not travel in political circles, nor is he well known in corporate America. He is the insider’s insider — a deal maker.

As such, his nomination to lead the Securities and Exchange Commission is a strong signal that financial regulation in the Trump administration will emphasize helping companies raise capital in the public markets over tightening regulation. In contrast, the agency’s two chairwomen under President Obama had regulatory or enforcement backgrounds.

Mr. Clayton, known as Jay, has spent nearly his entire career in corporate boardrooms. His regulatory experience stems from advising banks on dealings with the government and helping several financial institutions with their settlements related to mortgage securities.

He had a front-row seat to the financial crisis, advising Barclays Capital in buying the assets of the bankrupt Lehman Brothers in 2008 and Bear Stearns in its fire sale to JPMorgan Chase in 2007. He has advised on mergers and initial public offerings, including the biggest ever, the $25 billion offering by Alibaba Group of China in 2013.