There’s a strange phenomenon in the stock market that recurs from time to time. A popular stock, that has become a megastar and is shooting for the moon, suddenly falls back to earth; at least part way. The luster becomes tarnished.

This is why former Fed Chairman Alan Greenspan coined the phrase “irrational exuberance.” He was speaking of the entire market, but to some degree, individual stocks inspire the same enthusiasm. They may or may not have the greatest valuations, but they are most often exciting companies that have achieved great things. Greenspan used the term in 1996 regarding the tech stock run-up, but it would take another few years before the prediction saw real consequences.

And so it has been, with the prestige and reverence paid to the FAANG stocks; the high-flyers who have rewarded investors well and seemed to be on a dizzying trajectory. Who can argue that these market leaders, who have captured so much market share and distinguished themselves as stalwarts of growth and reward, did not deserve investor interest?

The FAANG stocks include Facebook, Apple, Amazon, Netflix and Google’s parent company Alphabet. They are all household names and brands with a powerful following, great services and products.

Through October, the FAANG stocks continued to perform and dazzle investors and new products and services seemed to help bolster their continued success.

Every Rally has a Hiccup

But, the stock market if fickle. There are no guarantees; only educated guesses. If a stock begins to appear overvalued or there are alternative safe-havens that look more inviting, the trend for that stock can reverse or correct.

During November, through the third week in the month, Netflix had lost 35 percent, Amazon was off by 26 percent and Facebook had fallen 40 percent. Facebook traded at $217.50 on July 25 and was sitting at $131.73 by November 23. Amazon hit $2,039.51 on September 4 and fell to $1,502.06 by November 23, with some new gains after exhibiting strong pre-holiday sales figures.

Apple, with its introduction of three new models recently, had hit $232.07 on October 3 and then fell to $172.29 by November 23 as the market questions the sales success of the new offerings. The company was forced to offer discounts to carriers after sales proved weaker than expected. Apple is also increasing their trade-in incentive. To placate nervous investors, Apple claims that their new XR model is the company’s best-selling iPhone. The iPhone represents 60 percent of Apple’s revenues.

For several of the FAANG companies, some of the luster has worn thin as there have been hints of corruption, questionable tactics for treating some socialmedia participants or arrangements with local governments that include overly-generous incentives. After having most of the public behind them, as pillars of the community who could do not wrong, even some groups of employees rebelled publicly.

It may not be irrational exuberance to invest in market share leaders, but an occasional pause, and reassessment, is always healthy.