RUNNING HEAD: Amplifying Counter-Public Spheres on Social Media Amplifying Counter-public Spheres on Social Media: News Sharing of Alternative vs Traditional Media after the 2019 Chilean Uprising Juan Pablo Luna 1,2 , Sergio Toro 1,3 , and Sebastián Valenzuela 1,4 1 Millennium Institute for Foundational Research on Data (IMFD) 2 Institute of Political Science and School of Government, Pontificia Universidad Católica de Chile 3 Department of Public Administration and Political Science, Universidad de Concepción 4 School of Communications, Pontificia Universidad Católica de Chile [Published in Social Media + Society on Feb. 24, 2022: https://doi.org/10.1177/20563051221077308 ] Corresponding Author Sebastián Valenzuela, School of Communications, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, C.P. 8331150, Chile. Email: savalenz@uc.cl Author Biographies Juan Pablo Luna (PhD, University of North Carolina at Chapel Hill) is Professor in the Institute of Political Science and the School of Government at Pontificia Universidad Católica de Chile, and Associate Researcher with the Millennium Institute for Foundational Research on Data (IMFD). His research interests include democratic representation, state capacity, and organized crime. Sergio Toro (PhD, Pontificia Universidad Católica de Chile) is Associate Professor in the Department of Public Policies and Political Science at Universidad de Concepción, Chile, and Associate Researcher with the Millennium Institute for Foundational Research on Data (IMFD). His research interests include the logic of representation in Latin American, political systems, and data science for public policies. Sebastián Valenzuela (PhD, University of Texas at Austin) is Associate Professor in the School of Communications at Pontificia Universidad Católica de Chile, and Associate Researcher with the Millennium Institute for Foundational Research on Data (IMFD). His research focuses on political communication, social media, and digital journalism. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: We gratefully acknowledge funding