Teva Pharmaceutical shares jumped 11 percent after Berkshire Hathaway reported a $358 million stake.
In a quarterly regulatory filing Wednesday, Warren Buffett's conglomerate reported holding 18.9 million ADRs of Teva. After spiking, Teva was still up more than 6 percent in after-hours trading.
At the same time, Berkshire has cut its holdings of IBM by 94 percent, to just more than 2 million shares. It also trimmed its Wells Fargo stake by 6 million shares to 458 million, and its stake in General Motors by 10 million shares, to 50 million.
The regulatory filing reflects Berkshire's stock holdings as of the end of December. Investment managers are required to report such holdings every quarter but with a delay.