Three months ago, industry data on second-quarter Internet ad spending generally painted rosy pictures for Alphabet Inc./Google (GOOGL) - Get Report and Facebook Inc. (FB) - Get Report going into their earnings report. And by and large, the companies validated those numbers: Facebook soundly beat Q2 estimates on the back of a 47% annual increase in ad sales, and though there was some disappointment over its larger-than-expected revenue-sharing payments, Google's gross ad sales rose 18% and were better than expected.

So what do industry figures suggest for Google's Oct. 26 Q3 report and Facebook's Nov. 1 report? They bode pretty well for Facebook continuing its long streak of sales and earnings beats, but paint a more mixed picture for Google.

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Standard Media Index (SMI), an online ad data provider that relies on spending figures from ad agencies and other market intelligence to create sales estimates, forecasts Facebook's North American ad sales (responsible for nearly half its Q2 ad sales) will rise 10.4% sequentially and 43% annually in Q3 to $4.91 billion. That's above a $4.86 billion consensus analyst estimate.

On the other hand, SMI forecasts Google's total Q3 ad sales will rise 2.1% sequentially and 17% annually in $23.15 billion. That's below a $23.5 billion analyst consensus.

Worth noting: SMI's estimates have been pretty accurate in recent quarters. During Q4 2016 and the first two quarters of 2017, there was only a 1% difference between the SMI's growth rate forecasts for Facebook's North American ad sales and Google's total ad sales and what the companies wound up reporting. And in Google's case, the estimate was always 1% too high.

At the same time, online ad agency Merkle's Q3 numbers paint a healthier picture for Google. Merkle reports its clients' U.S. Google search ad spend grew 24% annually, a rate slightly better than Q2's 23%. Interestingly, this growth was driven not just by strong mobile search ad spend -- spending for ads shown on phones grew 51%, easily offsetting a 23% drop in tablet spending -- but by a 25% increase in PC search ad spend.

Mark Ballard, Merkle's Director of Research, noted that Google's Q3 2016 decision to no longer require PC ad campaigns to also cover tablets is leading advertisers to spend more on them. He added a May change to Google's Ad Rank algorithm is contributing to higher spending on text ads that appear near the top of search pages. With ad prices for many popular search keywords still much lower on phones than PCs, PCs still matter a lot to Google.

And across devices, Google is still seeing booming sales for its Google Shopping e-commerce search ads, as retailers battling Amazon.com Inc. (AMZN) - Get Report continue flocking to them. Merkle saw Google Shopping spending growth improve to 37% from Q2's 31%, with the ads accounting for 53% of all search ad clicks seen by U.S. retailers. A big reason for this: The average amount of revenue retailers get from a Google Shopping ad click remains meaningfully higher than what they get from text ads.

Merkle reports a 40% increase in its clients' Facebook ad spend in Q3, after reporting 56% growth for Q2. But it's worth keeping in mind here that just 3% of the Facebook spending seen by the firm involves Instagram, which from all signs has been seeing very rapid growth. And whereas 87% of Facebook's Q2 ad spend involved mobile devices, 30% of the Q3 ad spend Merkle saw involved PCs, which are seeing slower ad growth.

Ballard observed that the number of Facebook ad impressions recorded by Merkle clients grew by 22% -- better than expected given Facebook's commentary about the company no longer planning to significantly grow its news feed ad load (the number of ads that appear on the news feed for a given amount of scrolling) going forward. He did caution, however, that impression growth is likely to slow in the coming quarters. The average price for Facebook ads sold on a per-impression (CPM) basis grew a moderate 7%.

For its part, social ad firm 4C Insights saw its clients' spending rise 27% sequentially and 150% annually on Facebook proper, and 55% sequentially and 220% annually. Notably, 4C also saw Facebook CPM pricing grow 9% sequentially, and pricing for Facebook ads sold on a per-click (CPC) basis rise 18%.

While 4C's gaudy spending growth numbers likely have much to do with the firm's own growth, its pricing data is encouraging and likely a reflection of how both targeting/measurement improvements and slower inventory growth are boosting the prices marketers are bidding for Facebook ads. "Features for measuring brand lift across Facebook and TV, driving offline outcomes, placing in-stream video ads across Facebook's Audience Network, and Facebook's detailed targeting and measurement capabilities are largely responsible for brands' continued investment in Facebook," 4C wrote.

On the whole, SMI, Merkle and 4C's Q3 numbers paint an encouraging picture for Facebook as it contends with its expected ad load slowdown. For Google, Merkle's numbers suggest Q3 was business as usual, but SMI's are (in light of the firm's track record) a little eyebrow-raising.

Facebook and Alphabet are holdings in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells FB or GOOGL? Learn more now.

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