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Warren Buffett said Monday that he hasn't been able to fully understand the way the global cloud computing business is developing, and that formed a big part of his decision to dump a $2 billion stake in Oracle Corp. (ORCL - Get Report)  earlier this year.

Berkshire Hathaway BRK.A told the SEC in its November filing that it had owned 41.4 million shares in Oracle at the end of the end of the third quarter after it had exited a holding in IBM (IBM - Get Report) earlier in the year. Buffett told CNBC's Becky Quick Monday that his IBM investment partly influenced his decision to exit Oracle, but that the larger impetus was based on a lack of cloud business clarity.

"Larry Ellison is doing a fantastic job, and it's a great business, but I still don't think I understand exactly where the cloud is going," Buffett said.

Oracle shares were marked 0.72% higher in pre-market trading Monday, indicating an opening bell price of $52.86 each, a move that would extend the stock's year-to-date gain to around 17% and value the Redwood City, California-based tech group at around $190 billion.

Oracle surprised investors with a bullish 2019 outlook late last year when it posted stronger-than-expected second quarter earnings and said growth in its cloud computing business would support sales and improve profit margins.

The company also said it sees current quarter earnings of between 86 cents and 88 cents a share, topping the 84 cent Street forecasts, and said it expects full year revenue growth of around 3% on a constant currency basis.

Oracle also revealed that earlier in the week its board authorized an additional buyback of $12 billion of common stock, under an existing share repurchase program.