Check out the companies making headlines midday Monday:
Under Armour — Under Armour shares cratered more than 18% after the apparel maker disclosed a federal probe into its accounting practices. The investigation has been ongoing since July 2017. The company also slashed its full-year revenue guidance, citing lower inventories and problems with its direct-to-consumer channels.
McDonald's — The Dow component fell 2.7% after CEO Steve Easterbrook was fired for having a relationship with an employee. "This was a mistake," Easterbrook said in an email. "Given the values of the company, I agree with the board that it is time for me to move on."
KB Home, PulteGroup — An analyst at Seaport Global Securities downgraded both housing stocks to neutral from buy, citing increasing cost pressures in an already "affordability constrained" environment. KB Home shares dropped 5.1% while PulteGroup slid 4.7%.
Marvell Technology — Shares of the chipmaker jumped more than 6% after a Wells Fargo analyst upgraded them to outperform from market perform. The analyst cited several reasons for the upgrade, including "continued, albeit modest, improvements in MRVL's traditional storage controller IC sales."
Ryanair — Ryanair's U.S.-listed shares jumped 8.7% after the discount airline posted quarterly results that topped analyst expectations. The company reported an 11% jump in traffic and added Georgia and Armenia to its "network."
Ferrari — Shares of the luxury car maker gained 5.3% after the company beat top and bottom line estimates. The company also raised its full-year guidance, fueled by strong sales of its Portofino and 812 Superfast models.
Occidental Petroleum — Shares of Occidental Petroleum jumped 4.6% ahead of its earnings release after the bell Monday. Analysts are expecting the company to have earned 38 cents per share in the third quarter, according to FactSet. The stock also got a boost from a 2% pop in crude oil prices.
Stryker, Wright Medical Group — Shares of medical device manufacturer Stryker sunk more than 3% after the company said it will acquire Wright Medical Group for $30.75 per share, valuing the deal at about $4 billion. Including debt, the deal is valued at about $5.4 billion. Wright Medical Group jumped 31.9% on the news.
Twilio — Shares of cloud communications company Twilio slipped 5.2% after the company re-reported its full-year forecast after flubbing the math the first time. Twilio's full-year earnings per share guidance is now expected to between 12 cents and 13 cents, instead of the 16 cents to 17 cents originally reported alongside its third-quarter earnings.
—CNBC's Maggie Fitzgerald, Yun Li, Pippa Stevens and Michael Bloom contributed to this report.