Check out the companies making headlines before the bell.

Union Pacific — Shares rose 9.5% after the company said CEO Lance Fritz would have a successor named this year. Bank of America upgraded the stock to buy from neutral following the news.

Seagen — Shares soared by 14.9% after The Wall Street Journal reported that Pfizer is in talks to acquire the cancer drugmaker, which has a market value of about $30 billion. 

Best Buy — The retailer slipped 1.5% in the premarket after being downgraded to market perform from outperform by Telsey Advisory Group. The Wall Street firm said it expects high inflation and rising interest rates to weigh on Best Buy’s 2023 sales and profits.

Berkshire Hathaway — Shares of Warren Buffett’s conglomerate could be active in premarket after the company reported Saturday that its operating profits fell during the fourth quarter amid inflationary pressures. Berkshire’s operating earnings totaled $6.7 billion last quarter, down 7.9% from a year ago. The Omaha-based company used $2.855 billion to buy back shares in the quarter.

Viatris — The health care company fell 1.5% after reporting fourth-quarter results. Adjusted net income for the period came in at $823 million, below a StreetAccount forecast of $850.4 million. Viatris also said former Celgene COO Scott Smith would take over as CEO, effective April 1.

Alliant Energy — Shares dropped more than 3% after the company reported that it intends to offer $500 million of its convertible senior notes due 2026. Net proceeds from the offering may be used for general purposes such as repayment or refinancing of debt, working capital and investments and repurchases, Alliant said.