Traders work on the floor of the New York Stock Exchange.

Check out the companies making headlines midday Monday:

Papa John's — Shares of the embattled pizza maker rose nearly 9 percent after the company announced Starboard Value has taken a $200 million stake in the company. Starboard CEO Jeffrey Smith was also named the new Papa John's chairman.

Maxwell Technologies — Tesla announced it was acquiring Maxwell Technologies for about $218 million, sending the energy technology company's stock up more than 49 percent. Maxwell makes devices that can store and rapidly deliver surges of energy. The deal represents a 55 percent premium over Maxwell's closing price on Friday.

Sysco — Sysco shares rose 4.8 percent the company reported quarterly earnings per share of 75 cents, topping analyst expectations by two cents. The company's revenue, however, came in slightly below expectations.

Clorox — Clorox reported better-than-expected earnings on Monday, sending its stock up 5.6 percent. The stock posted its biggest one-day gain since Aug. 2, when it rose 6.17 percent. The company also reiterated its 2019 guidance for earnings and revenue.

Alexion Pharmaceuticals — The pharmaceutical company's stock rose as much as 2.1 percent on the back of better-than-expected quarterly results. Alexion posted earnings per share of $2.14, well above an estimate of $1.82. However, the stock failed to hold its gains and closed 2 percent lower.

Allergan — Shares of the drug-maker fell 3.85 percent on Monday after a rival to its famous Botox injection was approved by U.S. regulators. Evolus says its competing wrinkle-fighting injection would be between 20 percent and 25 percent cheaper than the price of Botox. Shares of Evolus jumped last week after the approval.

Sonos — The stock rose 7.2 percent after Morgan Stanley upgraded it to overweight from equal-weight on the potential upside from its custom home installations and the IKEA partnership. J.P. Morgan also mentioned Sonos would be a good fit for Apple to make strategic acquisitions among Netflix and Activision Blizzard.

Apple — Shares of the tech giant jumped 2.8 percent midday Monday, bringing its year-to-date gains to 8.2 percent. The move higher comes after J.P. Morgan said Apple could acquire a major media player like Netflix.

CME Group — Shares of the derivatives marketplace fell after it reported its average daily volume was down 6 percent from a year earlier.

Roku — Roku shares opened little changed this morning and steadily climbed higher. The stock rose as much as 12.14 percent before closing 4.91 percent higher. It's unclear what the fundamental catalyst is for the jump as it's breaking out from its 200-day moving average.

Match Group – Shares of the dating service slipped 0.55 percent after Goldman Sachs began coverage with a sell rating. While Goldman said the parent company of Tinder has a "promising" long-term outlook, it thinks Match's valuation is "high relative to its growth." Goldman Sachs has a $45 price target on Match's stock.

—CNBC's Kate Rooney, Michael Sheetz and Yun Li contributed to this report.