 ThredUp Inc. slumped 4.3 in Tuesday premarket trading after the resale company made a number of announcements throughout Monday, including a business update and the launch of a public offering. ThredUp said during after-hours Monday that it would launch a public offering of 6,424,369 shares of Class A stock, including 2 million shares that will be issued and sold by the company, and 4,424,369 shares from existing stockholders. 