The FAANG stocks are Facebook, Amazon, Apple, Netflix and Google, a clutch of technology shares that have largely led the strong performance of the US equity market over the past year.
Facebook shares have risen from $1.22 (93p) to $1.72 (£1.31) over the past year. Amazon shares have risen from $7.67 (£5.84) to $10.20 (£7.77) over the past year.
Mr Roberts said on FAANG stocks: "It is questionable whether there is sufficient earnings support in the underlying businesses to warrant current valuations.”
Mr Roberts said that as an investors with income as a focus, he has shunned the FAANG stocks in favour of what he called “older tech” businesses where the dividend level is higher.
The yield on the Fidelity Global Dividend fund is 2.8 per cent. The dividend yield on the MSCI Global Equity Income sector is 2.6 per cent
Mr. Roberts noted that many of the FAANG shares either do not pay a dividend, or have a low yield.
He commented that the market fixation with FAANG shares has created an opportunity among what he calls the “less glamourous old technology companies”.
He cited Microsoft as an example of an “old technology” stock he believes is of particular value right now and in which he is invested.
Microsoft shares have risen from 56 cents (42p) to 73 cents (56p) over the past year.
The fund manager commented: “The fact that many of these tech companies don’t tend to pay a dividend means that the wider sector can often be overlooked or under-represented in global equity income portfolios."
Mr Roberts, an income investor, has around 11 per cent of the capital in the fund invested in technology shares other than the FAANG stocks.
The Fidelity manager's views are echoed by some other managers in the industry.
Simon Edelsten, who runs the £70m Artemis Global Select Fund, is also not keen on FAANG stocks.
He sold his Facebook shares in September 2016 as he feared for the sustainability of the advertising sales model from which the company derives its revenue.
More recently, Mr. Edelsten sold his Amazon shares as he takes the view that the company's recently announced acquisition of Wholefoods "takes the company slightly in the wrong direction" as grocery retail is a "capital intensive and low margin business.
However James Anderson, who runs the £6.1bn Scottish Mortgage Investment Trust, which has Amazon and Facebook among its top ten holdings, said the management of those companies "are thinking decades into the future, and so current valuations are not the best judge of future returns.
"The opportunity is massive," he said.