Check out the companies making headlines before the bell. Defense stocks 一 The group rose after a joint U.S.-Israeli attack on Iran over the weekend that was met with retaliation by the oil producing giant. Lockheed Martin shares also gained 6%, while Northrop Grumman was up 5%. Drone maker AeroVironment jumped more than 10%. Oil stocks 一 Several oil stocks surged following U.S. and Israeli strikes on Iran on fears the conflict could disrupt global crude production and transport. Exxon Mobil and Chevron shares gained about 4%, while ConocoPhillips was also up more than 5%. The cost of oil rose, with Brent crude prices hitting a new 52-week high of more than $78 on Monday. Tankers stocks 一 Shares surged following the eruption of military strikes in the Middle East. Frontline rose more than 5%, while DHT Holdings gained 7%, and International Seaways was up 6%. Travel stocks — The group slid as the conflict between the U.S. and Iran sent crude prices surging and disrupted global travel. Expedia and Booking Holdings shed 3.2% and 2.7%, respectively. Delta Air Lines slid 5.7%, while American Airlines and United dropped at least 6% each. Berkshire Hathaway 一 Class B shares fell 1% after the conglomerate posted an operating earnings decline of nearly 30% for the fourth quarter, due largely to weakness in insurance. Overall earnings, which include gains or losses from the conglomerate’s stock market investments, also fell slightly year on year. AES 一 The energy stock plunged nearly 17%. A consortium of investors led by Blackrock’s Global Infrastructure Partners and EQT said Monday it would acquire AES for nearly $11 billion . Under the agreement, shareholders will get $15 per share in cash. The deal is expected to close in late 2026 or early 2027. Elevance Health 一 Shares shed nearly 4% after the insurer said in a filing that the Centers for Medicare & Medicaid Services plans to impose sanctions on its operations, suspending enrollment of Medicare beneficiaries into its Medicare Advantage-Prescription Drug plans and temporarily halting certain communication activities to its Medicare beneficiaries. Bank stocks — Banks fell as rising tensions in the Middle East dented sentiment around global markets and the economy. JPMorgan Chase , Goldman Sachs and Morgan Stanley shed more than 1% each along with Bank of America . Citigroup slid 2.5%. — CNBC’s Fred Imbert contributed reporting.