Updated from July 21 to include research from Consumer Intelligence Research Partners in the seventh paragraph.

NEW YORK (TheStreet) –– Apple (AAPL) shares have surged since the maker of the iPad reported its fiscal second-quarter earnings in April. Investors will be looking to see whether iPhone sales remain strong ahead of the company's much-anticipated and perhaps, biggest product ever, coming in the fall: a larger iPhone.

For the quarter ended March 30, Apple shipped 43.7 million iPhones, on its way to earning $11.62 a share and $45.6 billion in sales. The company also shipped 16.4 million iPads, and shipped 4.1 million Macs during the quarter. Gross margin, a highly watched level for Apple, came in at 39.3%.

Following the report, Apple shares have gained 23.7%, compared to a 5% gain in the S&P 500 and a 6.3% gain in the Nasdaq.

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For the fiscal third quarter, Apple said it expects between $36 billion and $38 billion, but Pacific Crest Securities analyst Andy Hargreaves says the company can continue the iPhone momentum in this quarter, leading to a substantial revenue surprise.

"We expect Apple to sell 36.1 million iPhones and 14.3 million iPads in FQ3, which should drive revenue and EPS to $39.0 billion and $1.31, respectively," Hargreaves wrote in the note. "We believe results should act as a positive indicator of iPhone demand in front of the anticipated iPhone 6 launch, while iPad expectations could take another slight leg down. Although our revenue and EPS estimates are well ahead of the consensus sell-side estimates of $37.9 billion and $1.23, respectively, we believe they are roughly in line with buy-side consensus."

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