We study how personalized news aggregation for rationally inattentive voters (NARI) affects policy polarization. In a two-candidate electoral competition model, an attention-maximizing infomediary aggregates source data about candidates’ valence into easy-to-digest news. Voters decide whether to consume news, trading off the expected gain from improved expressive voting against the attention cost. NARI generates policy polarization even if candidates are office motivated. Personalized news aggregation makes extreme voters the disciplining entity of policy polarization. The skewness of their signals helps sustain a high degree of policy polarization in equilibrium. Analysis of disciplining voters informs the equilibrium and welfare consequences of regulating infomediaries.