Check out AQR's latest on the FANG stocks:
"a year and a half later, the FANGs are again in the press with similar claims they are the primary drivers of market performance"
"For the five months ending in May of this year, Google (now Alphabet but still the G in FANG), and Amazon were two of the top 3 contributors to market performance. As a result, there has been a renewed interest in the press regarding the FANGs and about another overly “narrow” market rally (there has also been some surgery to the list — Apple has been added by some turning the ‘FANGs’ into the ‘FAANGs’ and a recent WSJ piece added Microsoft and removed Netflix from the list so perhaps it is now the ‘FAAMGs’)"
The short answer is: this is not as unique or "narrow" as many headlines make it out to be.
"Putting all of this together, it means that some of the FAANGs will be back in these stories (for positive or negative impact) soon enough over some ex post time period (3 months, 5 months, 1 year, we’ll figure it out after it happens!). And it will likely be just as normal then as it is now and as it was after 2015 when Cliff first noted this."