The gaming and social media firm is one of several Chinese Internet companies whose prospects are suddenly in question after years of spectacular growth.
Rovio says it could list in the future, but declines to comment on a media report that Tencent is looking to acquire the company.
Tencent's $8.6?billion purchase of a majority stake in "Clash of Clans" maker Supercell comes as mobile game revenue soars.
Co-founder Mark Pincus relinquishes the last of his operational duties at the social gaming company, retreating to an advisory role.
The company aims to challenge Tencent in China's growing mobile gaming sector.