Stocks making the biggest premarket moves: PacWest, Berkshire Hathaway, American Airlines, AMC and more

Check out the companies making the biggest moves in premarket trading:

PacWest — The regional bank popped 39% in premarket trading, adding to its nearly 82% gain on Friday. PacWest said its business is “fundamentally sound” and cut its dividend by just 1 cent per share. Western Alliance gained about 11% while Zions Bancorp added nearly 6%.

Occidental Petroleum — The energy stock dipped less than 1% in premarket after Warren Buffett said Berkshire Hathaway doesn’t plan on taking full control of the oil giant. The “Oracle of Omaha” has amassed a stake of 23.5%, while receiving approval to purchase up to 50% of the company.

Berkshire Hathaway — The conglomerate’s B shares rose 1.4% in premarket after Buffett’s company reported a 12.6% jump in operating earnings in the first quarter. The strong performance was driven by a rebound in the conglomerate’s insurance business. Overall earnings also rose sharply thanks in part to gains in its equity portfolio, led by Apple.

Estee Lauder — Shares jumped 4.2% in premarket trading following a Sunday report from the New York Post that activist investor Nelson Peltz was contemplating a “possible shakeup” at the beauty products company. The campaign would reportedly target CEO Fabrizio Freda.

AMC — AMC slid 3% in the premarket after the movie theater chain said it reached an agreement to settle a shareholder class action against the conversion of AMC Preferred Equity Units into common company shares, as well as a reverse stock split. Investors approved the decision in March.

American Airlines — Shares gained about 3% in premarket trading Monday after JPMorgan upgraded the stock to overweight from neutral. Analyst Jamie Baker highlighted the company’s attractive valuation and said the “Big 3” airlines, which encompasses American, Delta and United, are pulling away from the broader field of providers.

Tyson Foods — Shares of the food production company tumbled 9% after Tyson cut its annual sales outlook and posted an unexpected loss for its latest quarter, according to FactSet. It also warned of a 4% decrease from the previous year in domestic beef production and flat pork production.

Viatris — Shares added 2.4% after the health-care stock topped earnings expectations and reaffirmed full-year guidance, despite a shortfall in revenue. Viatris posted $932.9 million in adjusted net income for the first quarter, ahead of the consensus estimate of $835.8 million from analysts polled by FactSet. Revenue, came in at $3.72 billion against a forecast of $3.8 billion.

Fortinet — The cybersecurity company added 3.3% after being upgraded to buy from neutral by Bank of America. The Wall Street firm cited Fortinet’s solid execution and strong underlying demand.

—CNBC’s Yun Li, Brian Evans, Alex Harring, Sarah Min and Tanaya Macheel contributed reporting.