The FTSE Developed Europe Index is a stock market index that tracks the performance of large and mid-cap companies from 15 developed European countries. The index is designed to measure the performance of the largest and most liquid companies in the region. It is a free-float market capitalization weighted index, meaning that the weight of each company in the index is determined by its market capitalization. The index is maintained by FTSE Russell, a subsidiary of the London Stock Exchange Group.