Apple reported its first profit decline in 10 years Tuesday and cautioned that sales could fall more than analysts expect over the summer.

Chief executive Tim Cook asked investors to think about the long-term success of the company — not short-term hiccups. Apple has exciting products “in our pipeline” that could come “in the fall” and throughout 2014, Cook said.

But Cook didn’t offer any specifics, and Apple’s cautious posture comes amid growing investor concerns that the tech giant isn’t keeping up with competitors in its key smartphone and tablets markets.

The company’s net income fell 18 percent, to $9.5 billion, in the first quarter, compared with the corresponding period last year. That beat analysts expectations, and revenue increased 11 percent, to $43.6 billion. But the combination of slower revenue growth and tighter profit margins was enough to unnerve some investors.

Apple gained nearly 2 percent to close at $406.13 Tuesday before reporting its quarterly results. In after-hours trading, the stock initially rose but cooled and was trading in slightly negative territory late Tuesday.

The firm’s shares have lost nearly a quarter of their value in 2013, erasing nearly all of last year’s gains. Cook acknowledged that the company’s recent stock decline has been “very frustrating for all of us.”

There was some good news for investors in the report. Apple announced that it will increase its stock buyback program from $10 billion to $60 billion. Its dividend program will grow by 15 percent. The new dividend, Cook said, will return $100 billion to its shareholders by the end of 2015.

But that was offset by lower-than-expected guidance for the second quarter. Apple forecast revenue of $33.5 billion to $35.5 billion during the next three months, below analysts’ expectations.

With no hint that it would debut a new product over the next few months, Apple may be giving its competitors an advantage, analysts said. Rivals have several news products planned, particularly its chief smartphone competitor, Samsung, which is debuting the Galaxy S4 this week.

“Samsung is setting the pace for product releases. Consumers and investors are expecting more from Apple,” said Sarah Rotman Epps, a senior anaylst at Forrester.

Apple customers tend to focus on a brand’s reputation rather than on specific features, and any indication that Apple is losing its cool factor to Android phone makers could be a big hit to the company, Epps said.

Apple fans, she said, are getting “antsy.”

Despite the concerns, Apple did report some impressive numbers. The company sold almost 4 million Macs — a 2 percent decline from the same period last year but a strong showing considering that PC sales plummeted more than 14 percent during that period.

And even without a new phone or tablet model to generate excitement, the company sold 19.5 million iPads and 37.4 million iPhones in the past three months, demonstrating strong demand for its existing products.

Critics have called on Apple to expand its audience by introducing a cheaper iPhone that could appeal to less wealthy, more price-conscious consumers in the United States and overseas, particularly China. But given that sales of older model phones remain strong, that is not likely, said Carolina Milanesi, a Gartner consumer technology analyst.

Sales of the iPhone 4 and 4S may squeeze profit margins, Milanesi said, but also show that the company can appeal to a wider audience with discounted, older models instead of hawking a lower-quality product that could tarnish its brand.

The sale of those older model phones also helped Apple expand its presence overseas, an important move as the smartphone market in the United States approaches a saturation point, she said. The company reported record sales of $8 billion in China, though growth slowed.

“Apple is going beyond the first-time adopters and the high-end segment and is reaching out to the mass market more and more,” Milanesi said.

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