Check out the companies making headlines before the bell. SanDisk — The maker of flash memory products, including memory cards, climbed more than 4%. The stock, spun off from Western Digita l last February, enters the S & P 500 on Friday. Tilray Brands — The cannabis processor and owner of Montauk Brewing slid 14% after declaring a 1-for-10 reverse stock split , effective at the Dec. 2 market open. The stock closed at $1.03 on Wednesday. CME Group — The parent of Chicago Mercantile Exchange, Chicago Board of Trade, New York Mercantile Exchange and Commodity Exchange fell 0.7% after saying its markets were halted due to “a cooling issue at CyrusOne data centers,” which stopped trading in U.S. stock index futures. Nasdaq Inc . was down 0.5% and Intercontinental Exchange , the owner of the New York Stock Exchange, was higher by 0.7%. Jefferies — The investment firm shed 1% after The Financial Times, citing people with knowledge of the matter, said the U.S. Securities and Exchange Commission was investigating whether Jefferies gave investors enough information on its Point Bonita fund’s exposure to bankrupt auto parts maker First Brands Group. Jefferies’ exposure to First Brands, which collapsed under a series of complex debt agreements, lifted concerns of other bad loans. Retailers — The country’s largest store chains were mostly higher on Black Friday, the unofficial start of the holiday shopping season often featuring large sales and discounts. Macy’s rose 1.5%, Best Buy added 0.4%, Walmart advanced 0.2% while Costco , Target and Dillard’s were fractionally higher.