The Warren Buffett Effect: Exxon Mobil's Stock Falls, Deere Rallies

Shares of Deere & Co. rallied 2% in premarket trade Wednesday, after Warren Buffett's Berkshire Hathaway disclosed that it acquired a new stake in the farm equipment maker during the fourth quarter. Deere's stock climbed 7.9% during the quarter, and has gained another 1.6% since then through Tuesday. Meanwhile, Exxon Mobil's stock slumped 1.3% ahead of the open, after Berkshire disclosed it sold off its entire stake in the oil company in the fourth quarter. The stock, a Dow industrials component, lost 1.7% during the quarter, but has gained 0.7% since then. The Dow gained 4.6% during the fourth quarter, and has advanced 1.3% so far this year.