Google parent company Alphabet missed Wall Streets quarterly revenue estimates for the first time in two years with its 2018 Q3 results, sending shares down almost seven per cent in after hours trading.

The search giants results served to strengthen investor concerns that big investments in new businesses, emerging competition and increasing regulatory scrutiny were combining to slow down the firms returns. The quarterly results also showed continuing erosion of the operating margin, as revenue growth slowed.

Overall revenue rose 21 per cent year-on-year to $33.74bn (£26.4bn), missing analysts estimates by around $310m. Ad sales contributed 86 per cent of those revenues, but growth slowed to 20 per cent from almost 24 per cent last quarter. Non-advertising revenue also came in below expectations.

“We continue to be pleased with the underlying momentum in our advertising businesses as we apply our strengths in machine learning ot improve the experience for users and advertisers,” said Ruth Porat, chief financial officer for Alphabet on the firms earnings call with investors. “As we noted, hardware was only a modest contributor in the third quarter as we launched a new Made by Google family of products for the fourth quarter holiday season.”

The company attributed much of the slower revenue growth to unfavourable currency exchange rates, but financial analysts also pointed to increased competition from Amazon, new privacy laws in Europe, and ad prices having been lowered to contend with antitrust concerns.

“Were seeing a larger-than-expected slowdown in Google properties revenue, representing its core search business,” said Monica Peart, analyst at eMarketer. “This is likely related to the ramp-up in competition from Amazon, as consumers increasingly turn to the eCommerce giant for their product searches.”