The Finnish Arvopaperi magazine has announced the ownership structure of Rovio, the creators of Angry Birds. The information has not come up in any IPO filing, but through public information in the Finnish governmental registry. The biggest chunk of the Rovio is owned by Trema Holdings International BV, the holding company of Kaj Hed. Kaj Hed is Mikael's father and Mikael is Niklas' cousin. It seems that Accel and Atomico, who together invested $42 million into the company last year, own around 20% of the company.
Below is the information based on the Arvopaperi magazine's article:
Kaj Hed / Trema International Holdings BV 69,7%
Niklas Hed 4,3%
Peter Vesterbacka 3,1%
Mikael Hed 0,6%
Accel Partners 10%
Atomico Invest 10%
Felicis Ventures 1%
This would mean that last year when Atomico and Accel Partners invested $42 million into the company, the post money valuation was exactly $210 million.
In another article by Tero Kuittinen in English in Arvopaperi, it is mentioned that current estimates in the US value the company between 6 and 9 billion dollars.
Update 7.17 GMT: We've found the missing 1% and added it to the table above. It belongs to Felicis Ventures. Thanks to @ElinaLappalaine for the info!