Stocks making the biggest moves premarket: FB, FDX, TSLA, NTRI, TVPT & more

Check out the companies making headlines before the bell:

NutrisystemThe weight loss program company agreed to be bought by Tivity Health for $1.3 billion in cash and stock. Tivity, a provider of fitness and health improvement programs, will pay $38.76 per share in cash and a little over a fifth of a Tivity share for each share of Nutrisystem, giving the deal an implied value of $47 per share. Nutrisystem closed Friday at $34.20.

TravelportThe provider of travel commerce platforms agreed to be acquired by affiliates of Siris Capital Group and Evergreen Coast Capital for $15.75 per share in cash, or about $4.4 billion. Travelport had closed Friday at $15.40, but the stock had jumped five percent last Thursday after reports that the deal was close.

FedExBank of America/Merrill Lynch downgraded FedEx to "neutral" from "buy", and cut its price target to $220 per share from $304. B of A/Merrill said the "surprise" change in management at the company's Express division may signal a reduction or delay achieving in its profit improvement target.

Facebook Facebook increased its stock buyback authorization by $9 billion, on top of a previously authorized $15 billion.

Gilead Sciences – Gilead named Roche executive Daniel O'Day as its new chief executive officer as of March 1, 2019. Chief patent officer Gregg Alton will serve as interim CEO from January 1 until O'Day's start date. The drug maker had said in July that CEO John Milligan would step down at the end of this year.

Deutsche Bank - A potential merger between Deutsche Bank and Commerzbank would have the approval of Germany's finance ministry, according to a Bloomberg report.

Visteon Visteon was downgraded to "sell" from "neutral" at Goldman Sachs, which expects an upcoming business update from the auto parts maker to be a negative catalyst for the stock.

WageWorks WageWorks was upgraded to "market outperform" from "market perform" at JMP Securities, which cites a number of positive factors for the benefits administrator including valuation.

Yelp - Yelp is under fire from longtime shareholder SQN Investors. The Wall Street Journal reports that SQN is planning to send a letter to the online review company's board pushing it to add new members and to consider all options to get Yelp back on track, including a sale. Yelp issued a statement noting that SQN had provided the letter to the media before sending it to Yelp, but said it is committed to maintaining an open dialogue with SQN and other shareholders, and that it regularly evaluates opportunities to unlock its full business potential.

Papa John's – Papa John's founder John Schnatter has engaged a financial adviser to help him review alternative for increasing shareholder value, according to an SEC filing.

Tesla – CEO Elon Musk told "60 Minutes" he does not respect the SEC, and that as largest shareholder in the automaker he can do anything he wants even if a new chairman is brought in.

Universal Display – The provider of organic light emitting diode technology sees its stock join the S&P MidCap 400 as of today. It replaces restaurant operator Sonic, which has been acquired by Inspire Brands.