Southwest Airlines aircrafts are seen at Baltimore/Washington International Thurgood Marshall Airport (BWI) on December 22, 2021 in Baltimore, Maryland.Alex Wong | Getty ImagesCheck out the companies making headlines in midday trading.Southwest — Shares dropped 6% after the company canceled 70% of its scheduled flights and warned that mass disruptions would continue “for the next several days.” Airlines had canceled thousands of U.S. flights over the last week in the midst of severe snow, ice, high winds and cold around the country.related investing newsLas Vegas Sands, Wynn Resorts — The casino stocks rose following China’s announcement that it will end quarantine for international travelers starting Jan. 8. Shares of Las Vegas Sands and Wynn Resorts have outsize exposure to the country given their operations in Macao. They added 4.2% and 4.5%, respectively.China-based companies — ADRs that are publicly listed in the U.S. traded up after the government announced the easing of Covid restrictions. Alibaba and JD.com each gained more than 4%. Baidu added 4.4%, and Pinduoduo rose 1.4%.Tesla — Shares of the electric-vehicle maker tumbled 11.4% on news that it will slow production at its Shanghai factory in January. The factory shut down at the end of December.Nio — Shares slid 8.3% after the electric-vehicle maker lowered its fourth-quarter delivery outlook due to supply chain disruptions in China.Peloton – The fitness company announced that it will offer refurbished bikes at a discount of up to $500 compared with new bikes. The stock was last down more than 8.4%.B. Riley Financial — Shares of the investment company climbed more than 1% after it released guidance for the fourth quarter. The company said it expects operating adjusted EBITDA of between $90 million and $100 million for the fourth quarter. That is down from the fourth quarter of 2021 but above some previous quarters this year. B. Riley also said it expected to end the year with more than $2 billion in cash and investments.Herbalife — The multilevel marketing company gained 2.4% following its announcement that interim CEO and Chair Michael Johnson would hold the role permanently. Johnson agreed to a salary of $1 and an equity-based incentive plan, according to the company.Coherus BioSciences — Shares dropped 11.8% following news that the company did not receive an action letter from the Food and Drug Administration for its nasopharyngeal carcinoma drug. The company said the FDA’s delay stems from its inability to tour a plant in China due to travel restrictions.— CNBC’s Samantha Subin, Jesse Pound, Tanaya Macheel and Sarah Min contributed reporting.