Stocks making the biggest moves premarket: U.S. Steel, Affirm, Illumina and more

Published Mon, Dec 18 20238:08 AM ESTUpdated Mon, Dec 18 202312:20 PM EST

Check out the companies making headlines before the bell. U.S. Steel — U.S. Steel shares popped more than 28% after Japan's Nippon Steel said it would buy the company at $55 per share, a deal that values the American steel company at $14.9 billion, including debt. Affirm — Shares of the buy now, pay later company fell more than 5% after Morgan Stanley downgraded Affirm to underweight from equal weight. The bank said its valuation is hard to justify downside despite the recent stock surge. Illumina — Illumina popped nearly 6% after the company said its plans to sell its Grail unit through a third-party sale of capital markets transaction, finalizing the terms by the end of the second quarter of next year. The news comes after a federal appeals court sided with the U.S. government in its challenging of Illumina's 2021 acquisition of the cancer test maker. Roku — Shares of the streaming video platform fell more than 3% after Seaport downgraded Roku to sell from neutral, citing increased competition in digital video advertising. Shares of Roku also fell more than 6% Friday. Adobe — Adobe shares rose 2% after the company agreed to terminate its $20 billion merger agreement with Figma as they face various regulatory obstacles. Structure Therapeutics — The clinical stage biopharmaceutical stock sank more than 42%. The move in shares came even after Structure Therapeutics said that its obesity drug showed promise in reducing weight and blood sugar. Uber — Shared inched marginally lower as the ride-sharing company readies to join the S & P 500 on Monday. Jabil and Builders FirstSource are also set to join the broad-based index, with shares last down 0.5% and up 0.5%, respectively. Vodafone — Shares popped 6.5% after French telecommunications company Iliad Group said it submitted a proposal to Vodafone to merge their Italian businesses. Sunnova Energy — Sunnova Energy's stock rose nearly 4% after Goldman Sachs upgraded the solar company to a buy rating, citing an improving growth setup for residential solar. — CNBC's Jesse Pound and Michelle Fox contributed reporting.