Warren Buffett just lost $1bn before lunch

Warren Buffett

Warren Buffett does not like to lose money in general, so losing $1 billion before lunch on a Monday morning can not be going down well.

The plunge in IBM shares Monday after its weak earnings results cost the Oracle of Omaha dearly. The stock fell $15.05 at the open, and Buffett held about 70.2 million shares as of June 30, according to the most recent SEC filings.

That means the sharp decline cost him $1.06 billion-a drop in the Berkshire Hathaway bucket, to be sure, but still noteworthy.

Read More IBM on earnings: We're disappointed

In April, after a prior weak earnings report, Buffett told CNBC he had not "soured" on IBM, that he had bought more stock this year and that he had not sold a share.

The stock was recently the third-largest holding in Buffett's portfolio, trailing onlyWells Fargo and Coca-Cola .

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