Buffett bought into IBM when its stock was near an all- time high, but it's been in decline since then as Amazon and Microsoft have dominated the cloud.
Buffet said Friday, "I don't value IBM the same way that I did six years ago when I started buying."
But Buffett says Berkshire Hathaway, which kicks off its annual meeting Saturday, could still buy IBM shares.
Two days ago, Moody's downgraded IBM's senior unsecured rating.