Critics 'dead wrong' on some big tech names, says RBC's Mark Mahaney

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Whether the end is nigh on the spectacular run-up in large cap U.S. techs, or they're back in market-darling territory, calls for caution persist.

In fact, with tech easily the best performing sector so far this year, there's no shortage of warnings on valuations.

"The critics are right and they're wrong," closely-followed RBC Technology Research Analyst Mark Mahaney told CNBC on Thursday.

"They're right with some of the lower-quality assets, but they're dead wrong when it comes to some of the higher-quality assets, there are still decent buys in the group."

Mahaney's "decent buys" are the so-called FANGs: Facebook, Amazon, Netflix and Alphabet (formerly trading as Google). Those are joined by two more: Priceline and Expedia.

"These are companies that are generating billions in free cash flow a year and their multiples, by the way, historically are lower than they were back in the bubble, back where they were ten years ago."

And for those looking beyond the typical stock picker's 12-month purview, Mahaney is watching three key tech sector themes: artificial intelligence, voice-activated internet and virtual reality.

AI is promising, he said, for its application in machine learning — to make sense of big data. "It's very hard to find where that is in the P&L, but it's going to be there in terms of improving the customization and personalization of these businesses."

Mahaney is watching voice-activated internet for its use in smart home systems, and virtual reality for its broad application.

On VR, Mahaney said: "That's really an unknown, there's so many issues that need to be worked out there, but could that be the next computing platform? Right now I think it's the front-runner to be."