The financial status is unclear. Originally Pulkovo were said to be taking over Rossiya but now it looks like the other way round.
Part of the rationale was that Pulkovo was a word little known outside St Petersburg (it is the name of the city's airport) and as Pulkovo Airlines wanted to expand away from their principal base it was desired to buy a company with a more "international" name - although I would have thought that just changing the name would be a little cheaper. Pulkovo have done charters out of Moscow to western Europe for a while now but seem to have little other non-St Petersburg activity.
Seeing as some of the Pulkovo fleet still sport what is basically their Aeroflot livery from more than 10 years ago, it will probably take a while before the new name becomes prominent.
For what it's worth, Aeroflot changed their name, half-heartedly, to Russia International Airlines in the 1990s, then changed back.