Author's Note: This post had been updated to reflect clarifications from Google on the presence of Google Express in Auction Insights reports.
Through the end of April, it appeared that Google Express’s presence in Google Shopping auctions was holding roughly steady at levels observed at the beginning of the year, even after Google’s March announcement of Shopping Actions. Google has clarified that Google Express impression share in Auction Insights does not reflect any impressions that might go to Shopping Actions 'transactional units', which are retailer-branded ads that land on Google Express, but rather indicate the presence of 'house ads' for Google Express advertising its marketplace.
While Auction Insights data on Google Express does not reflect Shopping Actions, it looks like Express is making moves and accounting for more Google Shopping impressions than we’ve ever seen before.
Google Express Impression Share Growing in Shopping
Google can place ads for Google Express products alongside traditional Google Shopping ads in the product ad carousel.

As mentioned previously, an analysis conducted in early May showed that while Google Express’s presence in Shopping auctions grew meaningfully during the holiday season in 2017, it's been steady ever since.
However, beginning just a few weeks ago we started to see Google Express impression share surge. Looking at a set of about a dozen advertisers that have regularly seen Google Express in Auction Insights reports at values greater than 10% (since less than 10% values are shown as ‘<10%’) since early May, we find that Google Express’s average impression share increased from 14% the week of 5/7 to 23% during the final week in July.

By the end of July, Google Express was one of the top ten biggest competitors in terms of Shopping impression share for all brands studied, and was even the competitor with he highest impression share for one advertiser.
Things seemed to really pick up steam in mid-June. By comparison, average impression share of the advertisers studied has remained roughly the same over the same time span.
Segmenting impression share by device, it appears Google Express’s presence has expanded across all three device types.

The advertisers studied deal in a wide range of products, including furniture, general home goods, novelty gifts, electronics, and more. Every member of the sample saw higher impression share from Google Express during the last week shown in the charts than the first.
All in all, it seems Google Express is growing in terms of Shopping presence. This comes at a time when Amazon is now back up to the visibility levels we saw at the beginning of 2018, following a brief decline and then complete shutdown of Shopping ads in the U.S. between late Q1 and early Q2.

Want to read more on Google Shopping Actions? Download our recent Dossier 9.1 report for our analysis on this and other recent developments.