What type of "informal business group" is the Mitsubishi company considered to be an example of?
Keiretsu: A keiretsu ( , literally "system", "series", "grouping of enterprises", "order of succession") is a set of companies with interlocking business relationships and shareholdings. Keiretsu:  The "keiretsu" maintained dominance over the Japanese economy for the second half of the 20th century.
i don't know