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Check out which companies are making headlines before the bell:

Apple — The tech giant will not aid the GOP presidential convention, citing presumptive nominee Donald Trump's comments on immigrants, minorities, and women, according to Politico.

Anthem, Cigna — The $44 billion merger between the two firms has raised antitrust concerns with U.S. regulators, according to The Wall Street Journal. Both companies have scheduled meetings this week with top U.S. Department of Justice officials, the Journal reported, citing people familiar with the matter.

Toyota Motor —The Japanese automaker is working on developing artificial-intelligence-based driving systems in five years, said Gil Pratt, the head of Toyota's advanced research division.

Federal-MogulIcahn Enterprises raised its offer to buy the manufacturing firm to $8 a share from a previous offer, made February, of $7 a share.

Dexcom — The glucose-monitoring developer said it had entered into a $200 million revolving credit agreement with a number of banks, including JPMorgan Chase and Bank of America, according to a Monday U.S. Securities and Exchange Commission filing. Dexcom said the agreement matures June 17, 2021.

Yelp — Deutsche Bank upgraded Yelp shares to "buy" from "hold," and increased its price target on the stock to $33 from $26, citing "stabilized salesforce productivity, more confidence in management, and improvements in ad units and systems bolstering our long-term outlook."

Pfizer — Jefferies trimmed its price target on the pharmaceutical giant's stock to $42 from $40, as Pfizer leadership gears up to decide whether to separate its global established business from the rest of the company.

Spirit Airlines — Analysts at Credit Suisse upgraded Spirit's shares to "outperform" and hiked their price target to $55 from $44, as second-half unit revenues look more favorable for the firm than its competitors, among other factors.

Corning — The company's stock was initiated with a "buy" rating and a $23 price target at Citi. "We believe sentiment in Display has turned too bearish into a typically seasonally stronger [second half], and note that screen size matters more than LCD TV unit volume," Citi said in a note to clients.

— Reuters contributed to this report.

Correction: This story has been updated to reflect Icahn's previous offer to buy Federal-Mogul was made in February.