Rubicon Project Founder Frank Addante has stepped down from his role as chief executive following an exodus of senior executives at the company over the last month and lowered revenue forecast in the company’s fourth quarter filing released after the market closed on Tuesday.

The Playa Vista company’s stock fell more than 22 percent in afterhours trading to $6.51 a share. The company’s stock has tumbled over the last year from a high of about $20 a share in April.

Michael Barrett, previously the chief executive of mobile advertising marketplace Millennial Media and chief revenue officer at Yahoo!, has been appointed chief executive.

Addante will continue to serve as the chairman of the board and will advise the company going forward. After founding the Rubicon Project in 2007, Addante said it felt great to step away from leadership of the company.

“I wouldn’t say stepping down, I would say I’m stepping across (to chairman of the board),” Addante said. “I think it’s what’s best for the company. My number one goal is the company’s success. What my title in that success is not important to me.”

Rubicon Project’s revenue for the quarter ended Dec. 31 fell to $72.7 million, compared to $94.0 million for the fourth quarter in 2015. The company posted a net loss of $21.2 million in the same period, compared to net income of $20.4 million for the fourth quarter of 2015.

The company issued revenue guidance of $41 million to $44 million in its financial filing below that of the analyst consensus revenue estimate of $57.3 million. The company’s President Greg Raifman and six other executives departed last month.