Pete Buttigieg released a list of his clients from his time at the consulting firm McKinsey & Company on Tuesday, after facing pressure from at least one of his opponents in the presidential race. The release comes after he was released from a nondisclosure agreement (NDA) that prevented him from being transparent about his work at the firm, which occurred between 2007 and 2010.

In a statement, the South Bend, Indiana, mayor provided brief descriptions of his work with each of his clients, which ranged from a nonprofit health insurance provider to U.S. government agencies.

"Voters can see for themselves that my work amounted to mostly research and analysis," Buttigieg said. "They can also see that I value both transparency and keeping my word. Neither of these qualities are something we see coming out of Washington, especially from this White House. It's time for that to change."

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In 2007, Buttigieg served Blue Cross Blue Shield of Michigan, where he said he focused on "overhead expenditure, such as rent, utilities and company travel." He was not assigned to work on health insurance plans, including premiums, benefits and policies.

His other clients included Best Buy, where he investigated ways to sell energy efficient products; the Environmental Protection Agency, where he researched energy efficiency; and the Department of Defense, where he sought opportunities to promote entrepreneurship in Afghanistan and Iraq. Buttigieg's last study at McKinsey was serving the U.S. Postal Service, where he analyzed new sources of revenue for the agency.

A spokesperson for McKinsey said in a Monday statement on that clients who are retained by McKinsey "expect impartiality and expertise rendered on a confidential basis" — but added the firm understands the "unique circumstances presented by a presidential campaign" and therefore granted Buttigieg permission to disclose his clients.

Senator Elizabeth Warren looks on as Mayor Pete Buttigieg speaks during the fourth Democratic primary debate of the 2020 presidential campaign. Saul Loeb / AFP

Private-sector concerns

Buttigieg also expressed concern "about efforts to demonize and disqualify people who have worked in the private sector for the sake of political purity."

"The majority of Americans have worked in the private sector at some point in their life," he said. "Good public servants, including recent Democratic presidents, have worked in the private sector at some point in their lives."

That includes Senator Elizabeth Warren, Buttigieg's rival, who has criticized his lack of transparency on the issue. Buttigieg has also criticized Warren for a related issue: not releasing her tax returns from her time in the private sector.

"I have released all my tax returns since I completed my education, a standard that, unfortunately, no other candidate in this race has been willing to meet," Buttigieg had said.

Warren had previously released a list of over 50 legal cases she worked on, as well as her tax returns dating back to 2008. On Sunday, after pressure from Buttigieg, Warren disclosed that she received $1.9 million in compensation for legal work dating back to 1987.

Read Buttigieg's full client list at McKinsey here:

2007: Blue Cross Blue Shield of Michigan

2008: Loblaws, Best Buy

2008-2009: Natural Resources Defense Council, Environmental Protection Agency, the Department of Energy, other nonprofit environmental groups, and several utility companies

2009: The Energy Foundation, U.S. Department of Defense

2009-2010: U.S. Postal Service