Vianney - there are quite a few established companies that publish journal ranings - as most of us know i.e. SJR, ISI etc - but there are far less who rank publishers. Those sources that do don't usually identify their ranking criteria or, if they do, the criteria tends to be subjective i.e. http://www.cityu.edu.hk/scm/pbpr_roa/ranking_sense.pdf
I'm not sure of the purpose for wanting to know this Vianney - but I would advise caution if it is ranking information for 'official' reasons.
Dear Vianney, it is a good thing that young or budding academics are curious about publishers and or journals ranking so you do not drop your publication in the wrong site. Nobody teaches this bit in any scientific class curriculum.
It however complicated to have all publishers evaluated with similar criteria because they publish for diverse and sometimes conflicting purposes (outreach, fund raising, charity, job creation, etc.) this makes ranking very subjective.
I would like to follow this question to have a broader view on publishers too.