Yunsong Guo is a staff software engineer at Pinterest, with expertise in machine learning and feature engineering based on large scale data analysis. He is a founding member of Pinterest Homefeed Ranking team, and is responsible for researching and developing machine learned ranking models for Homefeed recommendations. The series of models Yunsong deployed online over the past 3-4 years have increased Homefeed user engagement multifolds, directly contributed to Pinterest’s ~200M MAUs. Prior to Pinterest, Yunsong obtained his PhD from the Computer Science department of Cornell University, and worked as a quantitative researcher at Goldman Sachs London and Citadel Hong Kong on algorithmic trading and high-frequency trading.