With Google’s antitrust trial underway this week, there is still one crucial open question: How big is Google’s ad tech business?

The size of Google’s ad tech ecosystem—including Google Ad Manager, the ad server and exchange that serves publishers, and Display and Video 360, the demand-side platform for advertisers to buy ads—is a core factor in how this case gets decided and what happens to those properties if Google loses.

Newly released documents for the trial give a clearer picture of the scope of Google’s ad tech business, suggesting any new entity spun out of Google, would be almost too big for any buyer.

On Tuesday, prominent ad tech consultant Terence Kawaja, CEO of strategic advisory firm Luma Partners, issued an estimate that Google’s ad tech empire, if it were a standalone company, could be worth up to $95 billion, which would pose a problem finding any potential buyer. “You can’t divest $100 billion,” Kawaja said on Tuesday. “There is no buyer for it. [Google] would have to spin it off to shareholders, that’s how any forced remedy would manifest.” (Google parent company Alphabet is worth $1.8 trillion.)

A spun-out Google ad tech entity would be a “behemoth,” Kawaja told Ad Age. And the new company would “free up capital, free up management, to just run this part of the business,” Kawaja said.

Kawaja’s analysis was based on the total ad spend of Google’s six core ad tech properties, divided by the net revenue. Those figures were from 2020, so Kawaja forecasted growth to today and then applied standard trading multiples to come up with a rough estimate of Google’s ad tech valuation. In 2020, Google’s six ad tech properties generated $38.9 billion in total ad spend, with net revenue of $5.9 billion.

Also read: Google antitrust court documents reveal ad agency perks

The valuation of Google’s ad tech business comes from exhibits submitted by Google attorneys in recent weeks detailing the financials of Google Ad Manager, Display and Video 360, Google Ads, Ad Sense, AdMob and Google Campaign Manager 360. Most of those properties are outgrowths of DoubleClick, the buy- and sell-side ad technology platform Google bought in 2008 for $3 billion. The DoubleClick acquisition is now at the heart of the antitrust trial.

The U.S. Department of Justice kicked off its case against Google in the U.S. District Court for the Eastern District of Virginia, with opening arguments and the first witnesses taking the stand Monday. One of the possibilities, if Google loses, fails on appeals or settles, is that it could be forced to divest the ad tech assets.

Google’s commanding stake

The DOJ argues that Google has a monopolistic position with Google Ad Manager, alleging it serves 90% of publishers that use the ad tech tools to sell their online ad inventory. The DOJ has already called Tim Wolfe, Gannett’s senior VP of revenue operations, to the stand. The publishing giant has already sued Google in other federal complaints, claiming 60% of all its ad buyers come through Google.

The DOJ has also presented evidence that Google has used its privileged perch over publishers’ ad tech pipes to benefit its ad business that serves brands and ad agencies. Google has claimed that there is a bigger market for digital advertising that the DOJ is ignoring, one in which there is robust competition, with rival giants such as Meta and Amazon. Google also has rivals in ad tech, such as The Trade Desk.

Google’s ad tech financials are difficult to parse because of the variety of properties that generate revenue, for publishers and from advertisers. Also, analyzing the structure of a standalone Google ad tech business is difficult because it’s unclear if, say, Google’s DSP would spin off with the other publisher-facing ad tools. Still, a standalone Google ad tech business would open some opportunities to invest and innovate in ways Google has not been able to do while it has been under antitrust scrutiny, according to ad experts.

Also read: Google’s ad tech revenue uncovered

The financial data is proving to be a source of fascination among Google watchers. Until now, Google has never given a complete breakdown of how much revenue it generates from these ad tech properties, and it has been hard to compare them to other supply-side and demand-side platform ad tech businesses.

Ad Age previously reported on how one financial document showed Google’s “booked” ad revenue from its DSP—Display and Video 360—meant it has less revenue than the closest rival The Trade Desk. DV360’s “booked” revenue was $2.3 billion in 2020, compared to The Trade Desk’s gross billings of $4.2 billion, according to analyst Brian Wieser, who writes the Madison and Wall newsletter. Wieser did further digging into another set of financials, the same ones used by Kawaja, where Google breaks out the total ad spend across Google Ad Manager, DV360 and the other properties. By total ad spend, Google is larger than The Trade Desk: Total ad spend on DV360 in 2020 was $6.7 billion. Wieser attributed the discrepancy between “booked” revenue and total ad spend to the fact that the total ad spend included ad spending on Google’s own properties.

In a newsletter last month, Wieser had reported on the “booked” revenue showing that The Trade Desk is larger than Google's DV360, at least by that measure, which was surprising. The more detailed accounting sheds further light on the relative size of both rivals.

In Kawaja’s analysis, Google’s combined ad tech properties would be worth between $78 billion and $95 billion. For comparison’s sake, The Trade Desk is currently valued at close to $49 billion.

Impossible to know true size

“I think it’s important to understand how big the business is in context of the market in which Google competes, because they are the biggest player,” Wieser told Ad Age. “It’s been impossible to know the true size of the market. Moreover, we’ve never known, and still don’t know with any certainty, if they are 20% or 50% or more of any given market in which they compete.”

With Google Ad Manager, Google reported “booked” revenue of $7.4 billion in 2020 on total ad spend of $9.6 billion, a difference attributed to the exclusion of programmatic direct and programmatic guaranteed revenue in the “booked” revenue. Programmatic direct and guaranteed are ad deals arranged by publishers but transacted through Google-powered ad infrastructure.

Google’s supply-side ad tech business, serving publishers, represented about a quarter of the market in web display advertising in the U.S. in 2020, according to Wieser’s estimates. Google’s Display and Video 360 had about a 20% share of the web display advertising market in the U.S., according to Wieser.

Of course, Google’s financials come with caveats because even the company had to acknowledge, when submitting the accounting figures, that it had never so finely broken out revenue from each of its ad tech properties. Also, if Google has to spin out parts of its ad machine, it’s unclear if DV360 would join that new company or stay within Google proper.

Without DV360, Google’s publisher ad manager could be less valuable, according to Joe Root, CEO of Permutive, the publisher-side audience activation platform. If Google is forced to truly untie its sell-side ad tech from its buy-side ad tech, both could lose some unknown value because they don’t get the benefit of working together. In many ways, Google’s court case is about how it leveraged its ad tech for publishers to boost its knowledge—through exclusive access to market data—to improve its own ad business.

“It’s hard to quantify the value of Google Ad Manager, the ad server, as a standalone business,” Root said. “So, it is hard to say how much of the value of Google’s ads business is because it has this advertiser product and DV360, versus how much of its value comes from Google Ad Manager alone.”

Google Ad Manager on its own would compete more directly with supply-side platforms, such as PubMatic and OpenX, Root said. Those SSPs have been doing innovative work with publishers to improve how they curate inventory and have made other upgrades to managing ad auctions, and Google is lagging in some of those areas, according to Root. But as a standalone business, Google’s new ad tech entity could start to work with publishers in new ways.

“Google has work to do to catch up in that space,” Root said. “So I think with a standalone Google business, I can’t speak to the value of it, but I do believe that business will be competing more directly with the SSPs versus this enormous standalone ad tech business, which is worth $100 billion, and I’m not convinced that DoubleClick for Publishers [Google Ad Manager] on its own is that valuable.”