The Global 100 process begins each year on October 1, when the initial universe of the index is established. The companies in the initial universe are subject to to four examinations, and the companies that emerge make up the Global 100 Short List. Companies on the short list are scored on the basis of the priority KPIs of your specific GICS sector. The top overall performers in each GICS sector are included in the final list of 100 companies, based on the number of places reserved for each GICS sector.

http://www.corporateknights.com/magazines/2016-global-100-issue/2016-global-100-results-14533333/