Weak reports from Amazon and Alphabet hit Facebook, Netflix

So-called FANG stocks dropped in extended trade on Thursday following disappointing quarterly reports from Amazon.com Inc and Alphabet Inc, two of the group's components.

The weak results from Amazon and Google parent Alphabet were the latest setback for the high-growth quartet of stocks known as FANG, which also includes Facebook Inc and Netflix Inc.

Wall Street favourites in recent years, those stocks have been punished in a month of volatility for U.S. equities that has some investors worried a decade-old bull market may be ending.

After the bell, Amazon dropped 6 percent after the online retailer and cloud computing heavyweight's quarterly net sales rose to $56.58 billion from $43.74 billion a year earlier, but missed analyst estimates of $57.1 billion, according to Refinitiv data.

Alphabet missed analysts' estimates for third-quarter revenue, while rising expenses trimmed its operating margin for the third straight quarter, fanning concerns about regulatory scrutiny. Its stock fell 4.7 percent.

Reacting after hours, Netflix dipped 1.9 percent and Facebook, which reports results on Oct. 30, lost 1.5 percent.

Earlier on Thursday, all four FANG stocks rallied by between 3 and 7 percent, regaining some of the territory lost in recent weeks during a broad market selloff.