SAN FRANCISCO, United States — Amazon.com Inc's sales projections for the crucial holiday quarter disappointed, and third-quarter results missed Wall Street's targets, sending the online retailer's shares 9 percent lower.

Some analysts fear that the U.S. holiday shopping season, the biggest quarter for most retailers, might turn out weaker than anticipated. The company projected on Thursday net sales of between $27.3 billion and $30.3 billion for the holiday quarter, lagging the $30.89 billion analysts had expected on average.

After an unusually busy first half of the year that saw the online retailer spend on developing everything from mobile phones and Hollywood-style productions to grocery deliveries, investors were ready to see it curtail its ambitions somewhat and start delivering sustainable profits.

Instead, its third-quarter net loss widened to $437 million or 95 cents per share in the third quarter, from $41 million a 9 cents a year ago. That came in larger than forecasts for a loss of 74 cents a share.

Revenue also fell short of expectations, from a company known for consistently chalking up robust top-line growth. Net sales rose to $20.58 billion, but that lagged forecasts for $20.84 billion, according to Thomson Reuters I/B/E/S.

Shares in the company slid more than 9 percent to $284 in extended trade.

By Deepa Seetharaman; editors: Dave Gregorio, Cynthia Osterman.