in 2005, together with a partner, he founded the "four-quarters group", whose managing director and principal shareholder he is. the start-up consulting company of the group now operates under the name "four-quarters exist gmbh". since 2008, roski has also been a founder and managing director of "iksor gmbh" (family office & business angel) and since 2012 authorized representative of "mein-mikrofinanzierer gmbh", a state-accredited microfinance institution.