In an unexpected move, Millennial Media co-founder and CEO Paul Palmieri has stepped down from the chief exec role to join New Enterprise Associates(NEA), with ex-Yahoo revenue chief Michael Barrett taking over the top job at the mobile advertising network.

Paul Palmieri has resigned from his post as CEO and from its board of directors effective immediately, according to the company, with Barrett assuming the top role, as well as a place on its board of directors.

Palmieri will join NEA as venture advisor, with a special focus on technology, and the announcement comes as Millennial forecast combined revenues of up to $109m (including revenues from its Jumptap subsidiary) for the fourth quarter last year, and revealed details of its full earnings call.

a statement Palmieri said: “Some time ago, I expressed my desire to the board to transition out of the company, and return to working with early stage entrepreneurs.”

Barrett – formerly the chief revenue officer at both AOL and Yahoo, as well as AdMeld CEO – assumes the role immediately.

Barrett said: “The mobile market is on a steep growth trajectory and I look forward to building on the leadership position Paul and the team have created to bring Millennial to new heights. I have long admired the company’s ability to deliver superior monetisation to its publishers and developer partners and powerful ad solutions to its brand and performance advertisers.”

Palmieri helped co-found Millennial Media and took the company through its IPO, one of the earliest major mobile ad network public offerings, in 2012.