How TikTok broke the ad business

Is tiktok’s time up? As the social-media app’s chief executive, Shou Zi Chew, prepares for a grilling before Congress on March 23rd, TikTok’s 100m-plus users in America fret that their government is preparing to ban the Chinese-owned platform on security fears. Their anguish contrasts with utter glee in Silicon Valley, where home-grown social-media firms would love to be rid of their popular rival. With every grumble from Capitol Hill,…