Stocks making the biggest moves midday: General Dynamics, United Airlines, Spotify and more
The USS Truxtun (DDG-103) destroyer sits in dry dock at the General Dynamics Corp. NASSCO shipyard facility on the Elizabeth River in Norfolk, Virginia, on Jan. 9, 2018.

Check out the companies making headlines in midday trading.

Spotify — Shares of the music streaming service company fell 2.5% after Redburn Atlantic downgraded the streaming giant to neutral from buy. The firm said Spotify's new audiobook offer doesn't fit into its original forecast for margin expansion, while simultaneously stoking competition from Amazon.

Zscaler — Shares of the cloud security company rallied 4.2% following an upgrade to an overweight rating from Barclays. As a catalyst, analyst Saket Kalia cited a new growth opportunity in the secure access service edge, or SASE, cybersecurity segment.

Mirati Therapeutics — Shares of the cancer drug company fell more than 5% after Bristol Myers Squibb announced a deal to acquire Mirati for $48 per share, plus a contingent value right worth up to $12 per share. Mirati's stock closed at $60.20 per share Friday.

Tesla — The automaker's stock fell 2.3% in Monday trading upon news that the company's year-over-year sales declined 10.9% in China last month, according to data from the China Passenger Car Association.

On Holding — The sneaker maker rose more than 1% after Baird upgraded the stock to outperform from neutral. The firm said On's recent investor day reinforced its confidence in the brand's health and upcoming three-year pipeline of growth.

Motorola Solutions — Motorola added 3.3% after Bank of America initiated the stock at a buy rating. The bank cited solid pricing power, strong growth and a sustainable order pipeline.

Datadog — Datadog dropped 3.6% after Bank of America downgraded the cloud stock to neutral from buy, citing downside revenue risk from demand checks.

Oil stocks — Energy stocks soared following the escalation of the Israel-Hamas conflict over the weekend. Shares of Halliburton , CF Industries and Hess each respectively rose 6.5%, 5.5% and 5%.

Defense stocks — Similar to the energy sector, defense stocks also rallied on the back of rising conflict between Palestine and Israel. Northrop Grumman , L3Harris Technologies and General Dynamics respectively soared 10.8%, 9.1% and 8.4%.

Airline stocks — On a broader level, airline names were down after several major airlines suspended service to Israel following this weekend's attacks. United Airlines slid 5.3%, while Delta Air Lines and American Airlines shed 4.5% and 5.3%, respectively.

— CNBC's Yun Li, Tanaya Macheel, Sarah Min and Jesse Pound contributed reporting.