The stock was at $145.94 in premarket trading Monday.
"We feel fine or we won't own it. We've never sold a share of IBM. Periodically. we buy a little bit more," Buffett told CNBC's "Squawk Box" in an interview from Omaha, Nebraska. "We have not been an aggressive buyer, but we've been a buyer."
Buffett-run Berkshire Hathaway owns a 8.51 percent stake in IBM. "I think I can safely say we would be much more likely to buy more in the next 12 or 24 months than we would be to sell shares."
Buffett hosted the annual meeting on Berkshire shareholders on Saturday in Omaha.