Stocks making the biggest moves premarket: Nvidia, Oracle, Immunomedics, Delta, Nikola & more

Check out the companies making headlines in the premarket Monday:

Nvidia (NVDA) — Nvidia shares popped more than 6% in the premarket after the company announced it would buy fellow chipmaker Arm Holdings from SoftBank. The deal is valued at $40 billion and Nvidia will finance it through a combination of cash and common stock.

Immunomedics (IMMU), Gilead Sciences (GILD) — Shares of Immunomedics more than doubled before the bell on news the company will be acquired by Gilead for $21 billion, or $88 per share. The deal is expected to close in the fourth quarter of 2020. Gilead will pay $15 billion in cash for the cancer drugmaker and will finance the rest through newly issued debt. Gilead shares dipped 1.3%.

Oracle (ORCL), Microsoft (MSFT) — Oracle popped 8.7% on news that ByteDance has chosen the software company as its U.S. technology partner, rejecting Microsoft's bid to buy TikTok's U.S. operations. Microsoft shares were down 0.4%.

Pfizer (PFE) — Pfizer CEO Albert Bourla said Sunday night that the company's coronavirus vaccine could be distributed in the U.S. before year-end if it is found to be safe and effective. Pfizer shares were up 2.7% in the premarket.

Delta Air Lines (DAL) — Delta shares rose 1.3% after the company said it will use its frequent flyer program to back a new debt program worth $6.5 billion. Earlier this year, United Airlines (UAL) said it would use its own frequent flyer program, MileagePlus, to back a $5 billion loan.

Nikola (NKLA) — Shares of Nikola dropped another 6.7% as the electric truck maker faces allegations of fraud from a short seller, Hindenburg Research. In a press release Monday, Nikola said the allegations are "false and misleading, and designed to manipulate the market to profit from a manufactured decline in Nikola's stock price."

Micron Technology (MU) — An analyst at Goldman Sachs upgraded Micron to "buy" from "neutral," sending the stock up 3.8%. The analyst said Micron is "well-positioned competitively as it continues to execute on its tech transitions … and risk/reward on the stock skews positive."

Overstock.com (OSTK) — Overstock was initiated by a Needham analyst with a "buy" rating and a price target of $96 per share, implying an upside of 47.4% from Friday's close of $65.15 per share. The analyst said Overstock is "benefiting from external and internal factors that are driving an acceleration in revenue growth and market share gains." Overstock shares traded 6.5% higher.

Thermo Fisher Scientific (TMO) — Morgan Stanley initiated Thermo Fisher with an "overweight" rating and a price target of $485 per share, sending the stock up 1.9% before the bell. That price target implies an upside of 12.6% from Friday's close. "Driven by end market strength and share gains in Biopharma and emerging markets, we expect TMO to meaningfully outpace peers, with diversification and scale embedding best-in-class resilience and flexibility," a Morgan Stanley analyst wrote in a note.

MGM Resorts (MGM) — Shares of MGM Resorts fell more than 1% after a Goldman Sachs analyst downgraded the casino operator to "sell" from "hold." The analyst said he expects "a slower recovery in Las Vegas which will drive downside to consensus estimates and fundamental underperformance relative to peers."

Kroger (KR) — Kroger was downgraded to "neutral" from "buy" by a Bank of America analyst, citing a potential deceleration of same-store sales moving forward as restaurants start reopening. Shares of the grocery store chain slipped 0.9%.