It seems an understatement to say Zillow Group (NASDAQ:Z)(NASDAQ:ZG) has been busy the past few months. But if one thing is for sure, it's that the market will be listening closely when the online real estate specialist releases third-quarter results later this week. What should investors be watching when Zillow opens the door to its latest quarter?

On headline numbers, segment progress
First, recall that Zillow's current guidance calls for third-quarter "pro forma" revenue -- which adds perspective by assuming the company's February acquisition of Trulia would have closed at the start of the year -- of $175 million to $177 million, and pro forma earnings before interest, taxes, depreciation and amortization of $18 million to $19 million.

Within the top line, most of Zillow's revenue should continue to come from its core Marketplace segment, which is expected to grow 25% year over year and will be primarily reflected in three parts: first, real estate revenue, which increased 44% year over year last quarter to comprise more than 71% of total sales. Second will be mortgages, which jumped 44% in Q2 to roughly 6% of sales. And third will be Zillow's real estate CRM company Market Leader, which was officially sold in September to Constellation Software's Perseus Division after a strategic review and should comprise less than 6% of total revenue this quarter. 

Next, Zillow sees revenue from its Display segment (which was about 15% of total sales last quarter) staying roughly flat on a year-over-year basis. This reflects Zillow's decision last year to consciously underinvest in Display so it can better focus on shifting its sales mix to the more favorable Marketplace segment over the long term.

On visitors, agent advertisers, and emerging markets
Next, recall that in September Zillow officially completed its integration of Trulia several months ahead of schedule, an effort capped with the successful combination of the two companies' advertising products. At the same time, Zillow also unveiled its new "Premium Agent" advertising platform, enabling agents to seamlessly buy and manage ads across all four of Zillow Group's consumer-facing brands (Zillow, Trulia, Hotpads, and StreetEasy) -- a mouthwatering proposition considering those brands collectively served a massive 141 million monthly unique visitors last quarter alone. Listen for updates, then, on whether agents are responding favorably to the new platform. 

But we also shouldn't be surprised if Zillow experiences a decline in its number of agent advertisers. Zillow ended the second quarter, for example, with 101,297 agent advertisers, down from 103,415 in Q1. But management explained that decline was due to a combination of ending several short-term discounted products from Trulia, as well as a shift in sales teams' incentives to focus on growing revenue over adding sheer numbers of agent advertisers. As a result, Zillow's monthly revenue per advertiser rose 18% year over year to $375, aided by an increase in low-churn, high-value advertisers.

Finally, listen for updates on what Zillow calls "emerging markets," notably including Rentals and Mortgages. The Mortgages business is expected to continue its torrid pace of growth this quarter, and last quarter surpassed a $40 million annual revenue run rate. But Zillow CEO Spencer Rascoff has previously revealed that the smaller Rentals business has already exceeded its initial goal of reaching $10 million in annualized revenue -- something that took Mortgages four full years to do -- and should catch up to Mortages' current rate within the next several years. Helping Rentals in its quest to do so will be last quarter's successful launch of the multifamily oriented ad solution called "Zillow Rent Connect: Boost," as well as Zillow's appeal to improve the Rental process last week by adding income-based qualification functionality to the site.

Relatedly, we should receive some color on recent and future acquisitions, including the status and potential revenue contributions of Zillow's purchase of real estate document simplifier DotLoop, announced just before last quarter's report. Zillow is striving to become a one-stop shop for all things real estate online, so we can safely anticipate more complementary acquisitions down the road.

The road ahead
Finally, expect Zillow to give investors a fresh look at expectations for the rest of the year. For perspective, three months ago Zillow reaffirmed guidance for 2015 pro forma revenue of $690 million and increased its pro forma EBITDA outlook to a range of $85 million to $90 million.

Of course, it remains to be seen whether Zillow Group will adjust these ranges with so much moving so quickly at the company of late, from its shifts in advertiser focus to the now-complete Trulia integration and new acquisitions. But over the long term, it seems safe to say Zillow's focus will first remain on gaining market share in these early stages as the real estate industry steadily migrates online.

Steve Symington has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Zillow Group (A shares) and Zillow Group (C shares). Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.