Here’s a look at the companies making headlines in midday trading: Southwest Airlines — Shares rose 7% after activist hedge fund Elliott Management amassed a $1.9 billion stake in Southwest Airlines. The firm is seeking to replace Southwest CEO Bob Jordan and Chairman Gary Kelly. GameStop – Meme shares fell nearly 12% in volatile trading after a rollercoaster week. GameStop added to Friday’s sharp losses after investors reacted to the company’s earlier announcement that sales fell significantly in the first quarter and that it was selling more shares. Meme stock leader Keith Gill held his first livestream in several years on Friday, discussing GameStop, but offered no new arguments for his bullish thesis and his big bet. Huntington Bancshares – Bank shares fell more than 6% after updating its full-year guidance. Huntington is now calling for a 1% to 4% reduction in net interest income. He previously called for a range reflecting a 2% decline to a 2% rise. In its presentation, Huntington said it “expects sequential growth from the first quarter of 2024 with acceleration in the second half of 2024 and into 2025.” Advanced Micro Devices. Shares of the chipmaker fell 4.5% after Morgan Stanley downgraded the stock to outweight from overweight, saying investors’ expectations looked too high. KKR, CrowdStrike, GoDaddy – Shares of KKR, CrowdStrike and GoDaddy rose following the announcement that the three companies would join the S&P 500. The shares rose 11%, 7% and 2%, respectively. The S&P Dow Jones Indices announced Friday that companies are set to join the index on June 24 as part of its quarterly rebalancing, with Robert Half, Comerica and Illumina leaving the index. While Robert Half shares rose nearly 1.5%, Comerica and Illumina shares fell 3.4% and 1.9%, respectively. Apple — Shares fell nearly 2% after Monday’s iPhone Worldwide Developers Conference. The company introduced the new iOS operating system and features related to artificial intelligence. ReNew Energy Global shares rose 4.8% after Morgan Stanley raised its price target, saying its rating on the UK company remained strong. The company said ReNew is strongly positioned to participate in India’s energy transition. Planet Fitness – The gym chain rose 4.6% as Jefferies upgraded to a hold buyback. The bank said shares could rebound from recent declines as a new CEO takes the helm. Price hikes and adjustments to franchisee models could also help the stock, Jeffries said. DraftKings – Sports entertainment shares rose 3.1% after Morgan Stanley redesignated the company as a top pick. The firm said the recent legalization of a progressive tax on sports betting companies in Illinois led to excessive concerns about stocks that had a tough quarter. — CNBC’s Yun Lee, Alex Harring, Michelle Fox, Sarah Min, Pia Singh and Sean Conlon contributed reporting.