Costco is extending retail media into Google Shopping—not by acting as the advertiser, but by enabling brand partners to promote products that are sold through Costco. This reflects a broader shift in how retail media moves offsite.

In this episode, Mark Williamson explains how Costco aligned its data infrastructure to connect offsite demand back to products, inventory, and sales. Rather than treating offsite as a channel to add, Costco is focused on becoming available in the moments where consumer journeys actually begin.

The conversation uses Google Product Listing Ads as a starting point, but the real story is how retailers can connect identity, signals, and measurement to participate earlier in high-intent shopping behavior.

Topics covered:

• Why Costco is enabling Google Shopping for brand partners
• How this differs from brands buying search independently
• Why most offsite retail media has struggled to date
• The role of data infrastructure in connecting offsite demand
• What it means to be “available” in the consumer journey
• How high-consideration purchases change where media needs to show up

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