By JESSICA E. LESSIN And IAN SHERR

In one of its most closely watched earnings reports in years, Apple Inc. AAPL +1.87% eased Wall Street's biggest fears despite notching its first profit drop in more than a decade.

The Silicon Valley company's results for its second fiscal quarter surpassed analysts' estimates, and Apple boosted a program to return cash to shareholders by $55 billion to $100 billion by the end of 2015. The moves, which comes as investors have been agitating for the company to return more cash to shareholders, include stock buybacks and increasing quarterly dividends.

Apple's results—which included and 18% decline in profit and the slowest revenue growth since 2009—nevertheless underscored the resilience of its iPhone franchise. Sales of iPads were even stronger, with unit sales jumping 65%.

"We're very confident in our future," said Peter Oppenheimer, Apple's chief financial officer, in an interview. He added that "it a great time for Apple and it will continue to be a great time for Apple."

A less-positive undercurrent in Apple's results is a squeeze on gross profit margins, an important measure in the efficiency of the company's operations. The figures came in slightly lower than expected, as the company's product mix shifted to cheaper products like the iPad Mini.

The company predicted margins could shrink a bit more in the current period ending in June, while its revenue prediction was slightly lower than analyst expectations.

Apple shares rose as much as 6% in after-hours trading but were recently down less than 1% following the earnings announcement. The vicissitudes of Apple shares, which peaked last year above $700, are broadly felt. About one-fourth of all U.S. mutual funds that hold stock own Apple shares, according to Morningstar Inc.

For the quarter ended March 30, Apple reported a profit of $9.55 billion, or $10.09 a share, down from $11.62 billion, or $12.30 a share, a year earlier. Analysts had projected a per-share profit of $10. Revenue rose 11% to $43.6 billion.

The results helped ease some major concerns hanging over the Cupertino, Calif., company, whose years'-long growth streak has been wavering amid competition from Android-powered phones by Samsung Electronics Co. 005930.SE -1.33% and a delay in introducing new products.

Among the positive signs, Apple said it sold 37.4 million iPhones in the quarter, up from 35.1 million a year ago. Apple sold 19.5 million iPads, compared with 11.8 million the year before.

Executives also said a little more than usual about the timing of future products. Mr. Cook said on the call with analysts that the teams are working hard on "amazing new hardware software and services that we can't wait to introduce this fall and throughout 2014."

Apple's announcement on cash, which Mr. Cook said earlier this year the company had been examining, also settles questions about the company's plans for the stockpile, which grew to $145 billion at the end of March. Earlier this year, investors including David Einhorn lobbied the company to return more to shareholders.

Write to Jessica E. Lessin at jessica.lessin@wsj.com and Ian Sherr at ian.sherr@dowjones.com