Jeff Bezos is testing the patience of investors after Amazon.com Inc. missed analysts’ estimates for a second straight quarter, sending the shares tumbling 10 percent.

The world’s largest online retailer yesterday reported a second-quarter loss of $126 million, more than double what was predicted, even as sales climbed 23 percent to $19.3 billion. Expenses jumped 24 percent to $19.4 billion.

Amazon remains one of the most highly valued companies in the U.S., yet the business is losing some of its sheen as profits are dragged down by investments that Bezos, the co- founder and chief executive officer, is making in cloud computing, warehouses and gadgets such as the new Fire smartphone. While shareholders have been patient, they’re increasingly seeking signs that the long-term strategy will work.

“All of us understand making investments, and then there’s a point where investors don’t know what the payoff is,” said Michael Pachter, an analyst at Wedbush Securities Inc. in Los Angeles, who predicted that Amazon would report a quarterly loss. “What if they get to $200 billion in revenue and still don’t have profit?”

For years, shareholders have backed Bezos’s view that big investments are necessary to gain share because Amazon’s business opportunity is enormous and will pay off in the long run. In the process, the company has upended industries from bookstores and traditional retail outlets, to providers of Web- computing software.

CEO Strategy

Investors have rewarded Amazon with the highest valuation in the Standard & Poor’s 500 Index, currently trading at 569 times earnings. After climbing 59 percent in 2013, the shares of Seattle-based Amazon have declined 10 percent this year, underscoring investors’ trepidation about mounting expenses.

The stock declined 10 percent to $321.25 as of 8:02 a.m. New York time in early trading.

As Bezos has funneled more money to expanding distribution, grocery delivery services and smartphones and tablets, there’s little sign sizable profits are coming and Amazon issued a forecast yesterday for a wider loss in the third quarter.

“As long as there is money to pour into the business, they will be pouring money into the business,” said Sucharita Mulpuru, an analyst at Forrester Research in Cambridge, Massachusetts.

Web Services

Weighing on results is a price war in the cloud-computing market, where Amazon rents data storage and computing power to other companies. Amazon, whose cloud competitors include Google Inc. and Microsoft Corp., cut prices for its Amazon Web Services unit this year.

While Amazon doesn’t disclose specific sales for Web services, it’s part of the “other” category under North American sales in its financial statements, where revenue in the second quarter declined by 3 percent to $1.17 billion from the prior period.

“We had very substantial price reductions,” Chief Financial Officer Tom Szkutak said on a conference call.

Amazon’s lack of profits stands in stark contrast to Alibaba Group Holding Ltd., which has better margins and is planning an initial public offering soon. The Chinese Web retailer disclosed in a prospectus in May that its profit totaled $2.8 billion for the nine months ended Dec. 31 on revenue of $6.5 billion. Amazon earned $274 million for all of 2013 on sales of $74.5 billion.

Investment Cycle

The loss in the latest period was the biggest since the third quarter of 2012, when Amazon posted a $274 million loss. Looking ahead, Amazon projected sales of $19.7 billion to $21.5 billion for the current quarter. Operating losses are projected to be $810 million to $410 million, Amazon said.

Amazon is in an investment cycle, which benefits customers and will eventually end, said Szkutak, without specifying when that will be.

“We have a tremendous amount of opportunity,” he said. While it’s impacting short-term results, “we’ll obviously be looking to get great returns on invested capital.”

Amazon doesn’t disclose certain information that could shed a light on whether its investments are working. Key portions of its business are absent from its financial reports, including Kindle sales, membership figures for the $99-a-year Prime program, and the profit it collects from its main online store.

“You don’t learn anything from Amazon because they don’t answer any questions and they don’t provide any metrics,” Pachter said.

Capital Intensive

Amazon also didn’t give an update on its dispute with Hachette Book Group over digital-book sales. Both are seeking a greater share of e-book income, and Amazon blocked pre-orders for some of Hachette’s books earlier this year, including “The Silkworm,” a new novel by J.K. Rowling, writing under the pseudonym Robert Galbraith.

Bezos is spending to take Amazon further away from its roots as an online seller of books. As it makes that shift, the company is increasingly competing with large technology companies such as Apple Inc., Google, Microsoft and Samsung Electronics Co.

Amazon is shipping this week its Fire smartphone, a $199 handset that lets users take a picture of a product to find and buy it quickly from Amazon. Reviewers have panned the device, citing a weak battery, lack of applications and the gimmicky nature of its 3-D display. Szkutak declined to provide specific figures about orders for the new smartphone.

Strong sales or not, Bezos has proven with devices such as the Kindle Fire tablet that he’ll stick with a product and continue to invest, even if early models don’t prove popular.

“They keep investing in these incredibly capital-intensive businesses,” Mulpuru said.