Check out the companies making headlines in midday trading.

Union Pacific – Union Pacific's stock gained more than 10% after the company announced that its current CEO would step down in 2023. Bank of America upgraded the railroad operator to a buy from neutral rating, citing the leadership change.

Fisker – Shares of the electric vehicle startup surged more than 30% after Fisker maintained its 2023 vehicle production target and said it spent less than anticipated in 2022. To be sure, the company posted a larger-than-expected loss and revenue miss for the fourth quarter, according to StreetAccount.

Tesla – Shares of Tesla rose nearly 5.5% following a Reuters report that the company's Brandenburg, Germany plant of the electric vehicle maker hit a production rate of 4,000 vehicles per week ahead of schedule.

Albemarle — Albemarle shares popped 3% after Wells Fargo named it a signature pick, noting: "ALB remains our preferred growth name in chemicals, given its position as one of the world's largest low-cost lithium suppliers."

Freyr Battery — The battery maker's stock soared 13.2% after posted fourth-quarter results. "We expect 2023 to be a truly exciting and transformative year for FREYR and our 24M licensing partners as we move into live battery production," CEO Tom Jensen said in a statement.

Seagen — Shares jumped 10.4% after The Wall Street Journal reported that Pfizer is in early talks to acquire the cancer drugmaker, which has a market value of about $30 billion. There is no guarantee there will be a deal, according to the report.

Nomad Foods — The frozen food company added 8.3% following an upgrade to buy from neutral by Goldman Sachs, which called the stock an "attractive investment opportunity."

Frontier Communications — Shares rose nearly 5% after Raymond James upgraded the telecom stock to strong buy from outperform. The upgrade comes after Frontier posted on Friday better-than-expected results for the fourth quarter. The company also gave strong full-year EBITDA guidance.

Viatris — The health care stock lost 2.7% after Viatris reported earnings and announcing former Celgene COO Scott Smith would take over as CEO starting April 1. Shares were last down 0.1%, however.

Alphabet — Google's parent company gained 0.8% after Bank of America reiterated its overweight rating, citing the technology giant's opportunities within artificial intelligence.

Zillow — The online real estate platform gained 2.1% after JPMorgan initiated coverage of the stock with an overweight rating. The Wall Street firm said Zillow's core demand generation-based business model, solid margins and active share repurchase program will help the firm navigate the near-term industry challenges. JPMorgan's price target of $48 per share represents an upside of nearly 20%.

Pulmonx — Shares jumped nearly 6% following an upgrade to overweight from equal weight by Wells Fargo. The firm said the medical technology company's stock has an attractive valuation.

Krispy Kreme — The donut maker ticked up but closed unchanged following an announcement that McDonald's will begin selling Krispy Kreme donuts at 150 locations in Kentucky for a limited time starting next month. The fast-food chain first tested the donuts at its locations in October. McDonald's ended the session up 0.4%

— CNBC's Samantha Subin, Pia Singh, Yun Li and Tanaya Macheel contributed reporting