Marissa Mayer is back with a new startup focusing on artificial intelligence

Marissa Mayer vanished from the Silicon Valley landscape two years ago when she resigned from Yahoo Inc. shortly after it was sold to Verizon Communications Inc. for $4.48 billion. Her tumultuous 5-year reign at the eponymous tech media company, on the heels of a historic run at Alphabet Inc.'s GOOGL, -1.03% GOOG, -1.06% Google in the search division, made her one of the industry's most recognizable faces -- to her professional benefit and personal dismay. On Monday, at the Techonomy conference here, she resurfaced with a new startup and some pointed comments on the valley. Mayer was interviewed on stage for about 20 minutes by Techonomy founder and journalist David Kirkpatrick. Like Twitter Inc. TWTR, 0.82% Chief Executive Jack Dorsey, Mayer opposes automated ads from politicians, calling them "very dangerous."