Before revision:  We analyze affiliation information of 8.5M authors from 40 countries , who published 8.9M scientific articles in 14 disciplines since 1996. We find that multiple affiliations occur both within countries as well as across borders, and that more than 60\% are within the academic research sector. The share of authors with multiple affiliations increased substantially over the past two decades and particularly since the mid-2000s.
After revision:  We analyze affiliation information of 8.5M authors from 40 countries we document that: In 2019, almost one in three articles was (co-)authored by authors with multiple affiliations and the share of authors with multiple affiliations increased substantially over the past two decades and particularly since the mid-2000s.