Amazon posted a $437 million net loss for the third quarter, or a loss of 95 cents a share, significantly deeper than the net loss of 74 cents per share expected by analysts polled in advance by Thomson Reuters.

Net sales were up 20 percent to $20.58 billion, but that was also less than analysts’ expectations of $20.84 billion for the quarter. Amazon projected fourth quarter sales between $27.3 billion and $30.3 billion, growing 7 percent to 18 percent compared with fourth quarter of 2013.

Shares of Amazon sunk more than nine percent in after-hours trading, following the earnings report. The stock is off 21 percent so far this year.

It marks yet another unprofitable quarter for Amazon, which during the second quarter showed a net loss of $126 million. It posted net income of $108 million during the first quarter.

Amazon.com has been investing heavily in all aspects of its business in recent years, expanding into areas such as hardware, media, advertising and cloud services. It is also boosting its spending on fulfillment centers, the massive warehouse where the company sorts, packs and distributes products. During the third quarter, Amazon.com spent $2.64 billion on fulfillment, up 29 percent over the same period last year. Marketing expenditures also are on the rise, coming in at $993 million, compared to $694 million for the same period in 2013.

The company employed 149,500 people at the end of the third quarter— up from 109,800 for the same period last year.

Those investments have come with a cost and provoked doubts from some Wall Street naysayers, though the Seattle-based company still commands a whopping stock market valuation of $144 billion.

Follow-up: Holy, crap: Amazon added 40,000 employees in the past year, nearing 150,000 staffers worldwide … Amazon takes $170M write-down on Fire Phone

Here’s the full press release: