About a year after CliftonLarsonAllen was formed through the merger of two major Minnesota and Wisconsin accounting firms, a longtime leader from the Wisconsin-based entity has exited the company—which will now proceed under the direction of its Minneapolis leader.

Minneapolis-based LarsonAllen, LLP, merged with Milwaukee, Wisconsin-based Clifton Gunderson, LLP, in January 2012, forming CliftonLarsonAllen, LLP. Following the completion of the merger, CliftonLarsonAllen was led by co-CEOs: LarsonAllen’s Gordon Viere was appointed to oversee the firm’s holding company, as well as its wealth advisory and outsourcing practices, while Clifton Gunderson’s Krista McMasters oversaw the company’s public accounting practice.

McMasters, however, resigned on Monday, and CliftonLarsonAllen recently announced that it has appointed Viere as leader of the entire firm.

CliftonLarsonAllen Chairman Steve Meindl said in a statement that the company’s board reviewed its co-CEO structure and “determined that operating under the leadership of one CEO will increase the pace of integration of our two firms and give better definition to our firm’s strategic initiatives.”

CliftonLarsonAllen spokeswoman Ellen Trytek told Twin Cities Business that McMasters was offered several other positions at the firm but decided of her own accord to exit the company. “Over the next few months, McMasters will be exploring new opportunities in business and board service, which leverage her leadership, experience, and passion for growing people,” the firm said in a press release.

McMasters joined Clifton Gunderson as an associate accountant in 1978 and served in several other roles before being promoted to CEO in 2009. She was the first and only woman to serve as CEO of one of the nation’s 50-largest certified public accounting firms, according to CliftonLarsonAllen. McMasters and Viere were credited for spearheading the merger of their firms.

Viere’s “longevity with the firm made him a natural fit” to take the reins as its sole chief executive, according to Trytek.

Although its primary leader will be based in Minneapolis, CliftonLarsonAllen will maintain its co-headquarters in Milwaukee and Minneapolis, Trytek said, adding that the firm’s leadership is also spread among other U.S. offices.

CliftonLarsonAllen is Minnesota’s largest accounting firm based on CPA-certificate holders in Minnesota, of whom there were 353 as of April 2012. The firm has more than 3,600 employees at more than 90 offices throughout the United States.