Sundar Pichai, CEO of Alphabet and of Alphabet’s wholly-owned subsidiary Google, in addressing anti-trust questions regarding Google’s ad-tech business, claimed that

Ad technology is a small part of what Google does, he said, and doesn’t make up a significant share of the company’s revenue, according to people familiar with the meeting [Pichai’s with Senator Mike Lee (R, UT)].

That begs a number of questions though. Questions being begged include these:

• How much ad-tech revenue is there in the aggregate in the ad-tech market?
• How many players are there in the ad-tech market?
• How much ad-tech revenue is taken in by the (let us say) 5 largest players other than Google?
• How much non-ad-tech revenue do those 5 largest take in with which they can buffer downturns in the ad-tech market compared to Google’s non-ad-tech revenue?

Regarding that last question,

…the parts [of Alphabet’s/Google’s revenue] that mostly relate to brokering the buying and selling of ads on other websites—generated about $31.7 billion last year, or about 12% of its revenue.

That suggests that Alphabet/Google has around 88% of its revenue from non-ad-tech sources with which to buffer its ad-tech in/outflow.

In the end, it doesn’t matter how much or little Google’s ad-tech revenue is in Google’s scheme of things. What matters is how much or little Google’s ad-tech revenue is in the ad-tech market place.