For Apple (AAPL) - Get Report  and its investors, it's about one thing and one thing only -- how many iPhones did it sell.

Apple's fiscal first-quarter is always its most important, given the impact of the holiday shopping season and iPhones, as well as Apple Watches and iPads being given as gifts. Goldman Sachs analyst Simona Jankowski isn't expecting any major surprises, but noted that iPhone supplies during the period could've been an issue.

"We expect a largely in-line fiscal first quarter, as iPhone upside was capped despite strong U.S. demand due to supply constraints that lingered into early Dec.," Jankowski wrote to investors in a research note, previewing earnings.

Analysts surveyed by Yahoo! Finance expect the company to earn $3.22 a share on $77.38 billion in revenue for the first quarter.

In addition to the iPhone, of which Wall Street is expecting around 77.5 million units to have been sold, analysts will be looking to hear any more color on the Apple Watch, as well as Apple Music and how the company's Services business is doing.

Apple has not historically released Apple Watch sales figures, with CEO Timothy D. Cook previously saying he did not want to disclose the sales figures as a way of helping out the competition. In the most recent quarter, Apple's Service business, which includes Apple Music and the App Store, saw revenue grow 24% year-over-year to $6.3 billion.

Over the past 12 months, shares of Apple gained nearly 25%, compared to the near 19% gain in the S&P 500.

Here are three ETFs that may benefit if investors like Apple's fiscal first-quarter results.

iShares U.S. Technology ETF

The $2.94 billion iShares U.S. Technology ETF (IYW) - Get Report has Apple make up 15.81% of its portfolio, charging investors an expense ratio of 0.43%.

Credit Suisse analyst Kulbinder Garcha -- who rates Apple outperform with a $150 price target -- believes iPhone shipments could be better-than-expected, citing supply chain data. "We believe that recent data points from the supply chain suggest that overall iPhone shipments remain in line to ahead of expectations, with potential for a stronger mix," Garcha wrote to investors, previewing earnings.

Technology Select Sector SPDR Fund

The $14.1 billion Technology Select Sector SPDR Fund (XLK) - Get Report has Apple make up 13.41% of its portfolio, charging investors an expense ratio of 0.14%.

Pacific Crest Securities analyst Andy Hargreaves noted that any weakness in Apple shares should be bought, given the long-term outlook of the company. "We recommend owning Apple and would be buyers on any meaningful pullback," Hargreaves wrote to clients. "In-line results appear likely, which may keep the stock range-bound in the near term. However, the coming iPhone cycle offers the potential for significant average selling price and gross profit dollar expansion, which should drive Apple higher through 2017."

Pacific Crest has an overweight rating and a $127 price target on Apple.

Vanguard Information Technology ETF

The $10.32 billion Vanguard Information Technology ETF (VGT) - Get Report  has Apple make up 13.19% of its portfolio, charging investors an expense ratio of 0.14%.

Goldman Sachs's Jankowski, who has a buy rating and a $133 price target, believes that the iPad and Apple Watch were strong during the quarter, which may help with weaker-than-expected iPhone sales, due to supply constraints.

"While our fiscal first quarter iPhone estimates are a touch below consensus (76.6mn vs. 77.6mn), we see upside driven by the Watch and iPad, which were strong sellers during the holidays," Jankowski wrote to clients. "Indeed, our survey implies an over 20% year-over-year increase in iPad sales and 50% increase in Watch sales in the U.S. over the holidays."