The Sales Your Ads Can't See: Introducing Subtotal Signal

TL;DR: Subtotal Signal sends purchase data from retailers and marketplaces like Walmart, Amazon, and Target to ad platforms as conversion events. Shoppers share that data by linking their retailer accounts to a brand through Subtotal Link. Meta is the first supported ad platform, where Subtotal Signal events can be used for conversion reporting, custom audiences, and lookalikes.

Your ad platforms can't see your retail sales

Imagine a skincare brand that runs a $50,000 campaign on Meta. Meta reports that the campaign drove more than 1,000 conversions, and every one of them is a sale that happened on the brand's own website. But the same ads also sent shoppers to Walmart, Amazon, and Target, and plenty of them bought there instead. Count those retail and marketplace purchases, and the brand made closer to 10,000 sales during the campaign. Those sales (what ad platforms call offline conversions) never make it back to Meta, so they're missing from the campaign's reported results. On paper, the campaign barely broke even. In reality, it may have been one of the best things the brand ran all quarter.

The problem isn't the campaign. It's the reporting. Ad platforms like Meta only count the conversions they're told about, and for most brands that means purchases on their own site. For omnichannel and retail-focused brands, where a big share of sales happen somewhere else, a campaign's reported performance is incomplete until offline conversions are tracked too.

The gap is bigger than it looks

Stores still dominate. Even after years of ecommerce growth, online sales account for only about one-fifth of U.S. grocery spending, according to NielsenIQ. And even online, EMARKETER estimates that brands' own direct-to-consumer sites capture less than 20% of U.S. ecommerce sales. For most consumer brands, the purchases an ad platform can see are a small slice of the total.

That gap has real consequences. Campaigns that are working look like they aren't. Budgets get pulled from the channels driving retail demand. Optimization algorithms learn from a small, unrepresentative slice of your buyers, the ones who happen to purchase direct, and keep chasing more people like them. The result is a measurement system that consistently undervalues the ads doing the most work.

What Subtotal Signal does

Subtotal Signal is a Subtotal product that sends purchase data from retailers and marketplaces to advertising platforms as conversion events.

It starts with Subtotal Link. When a shopper connects a retailer or marketplace account (say, their Walmart or Amazon account) to your brand's site or app, they're choosing to share their purchases with you. Subtotal identifies the items in those purchases that are your products. Subtotal Signal then takes eligible purchases and delivers them to your ad platform, where they can be evaluated against your shoppers' ad interactions.

In short: purchases that used to be invisible to your ad platforms become events those platforms can match, measure, and optimize toward. And because the data comes from the shopper's own linked account, it reflects what they actually bought, not a modeled estimate. For the full flow, see How Signal works and the Subtotal Link introduction.

Two events: account linked and purchase shared

Subtotal Signal sends two kinds of events.

Account linked. This fires the first time a shopper successfully connects a supported retailer account to your brand. It carries no dollar value; it's a signal that someone raised their hand and chose to share their purchases with you. You can measure it as a conversion in its own right (useful if you're running campaigns to grow your connected customer base) or use it to build audiences. Reconnecting an account that's already linked doesn't create a duplicate event.

Purchase shared. This fires when an eligible purchase from a linked account is shared. The value of the event is only the value of your products in that order. If a shopper spends $60 at a retailer and $24 of it is your products, the event is worth $24. Your reporting reflects your order value, not the whole basket.

Audiences built on your retail buyers

The same events power audiences. You can build custom audiences of people who linked an account or bought your products at retail, then retarget them or use them as seeds for lookalike audiences. That means your prospecting can be modeled on your actual Walmart, Amazon, and Target buyers, not just the smaller group who buy on your site.

Starting with Meta

Meta is the first advertising platform Subtotal Signal supports. Signal sends events through Meta's Conversions API to the datasets you choose, and you decide which events to send and which retailers each dataset receives. Once it's set up, events show up in your Meta dataset in Events Manager, usually within an hour, where you can use them for campaign reporting, custom audiences, and lookalikes.

Purchase events arrive as SubtotalPurchase by default. Account-linked events arrive as SubtotalAccountLinked. Each event also carries useful detail, including which retailer the purchase came from and whether it was online or in store, so you can filter and segment in Meta the same way you would with your own data. If you already send retail purchases to Meta through another provider, don't send the same purchases through both, or they'll be counted twice. See Set up Meta and Meta events and data for specifics.

Meta decides what gets credit

Subtotal Signal delivers the purchase event, and Meta decides whether to credit it to an ad. Meta first tries to match the shopper to a person on its platform, then applies its own attribution rules and your settings. Not every event will be matched or attributed, so it's normal to see events in Events Manager that don't appear as attributed conversions in campaign reporting. Signal also only sees purchases from shoppers who have linked a retailer account and haven't opted out, so it won't capture every retail sale. How much of your retail sales it reflects depends on how many of your customers choose to connect.

More complete reporting can also raise your reported ROAS on its own. That's added visibility, not new sales, so use a controlled test to measure whether Signal improves campaign performance.

Shoppers choose what's shared

Shoppers decide what gets shared: purchase data only comes from people who choose to link a retailer account to your brand. Before event delivery is turned on, brands also set up a process to pass consumer opt-out requests to Subtotal, and opted-out shoppers' data isn't sent to ad platforms. Details are in Consumer choices and opt-outs.

Who Subtotal Signal is for

Subtotal Signal fits best if a meaningful share of your sales happen through retailers and marketplaces and you're investing seriously in paid media. If that describes you, your ad platforms have likely been making decisions with most of your sales missing. Subtotal Signal gives them the rest of the picture.

FAQs

What is Subtotal Signal?

Subtotal Signal sends purchase data from retailers and marketplaces to advertising platforms as conversion events. It lets brands measure and optimize ads against retail sales, not just DTC sales.

Which ad platforms does Subtotal Signal support?

Meta is the first advertising platform Subtotal Signal supports. Events appear in Meta Events Manager as SubtotalPurchase and SubtotalAccountLinked.

Can I measure Walmart or Amazon sales from my Meta ads?

Yes, for shoppers who link their Walmart, Amazon, or other supported retailer accounts through Subtotal Link. Subtotal Signal sends their eligible purchases of your products to Meta, and Meta decides whether each purchase is matched and attributed to an ad.

Does Subtotal Signal send past purchases?

No. Signal sends eligible purchases from the last seven days, so linking an account or turning on Signal doesn't send a shopper's full purchase history. Each event keeps its original purchase date.

Does Subtotal Signal decide attribution?

No. Subtotal Signal delivers eligible purchase events. The ad platform handles matching and attribution based on its own rules and your settings. An event is delivered when Meta accepts it, matched when Meta connects it to a person, and attributed when Meta credits it to an ad interaction. Not every delivered event gets matched, and not every matched event gets attributed.

How are shopper opt-outs handled?

Brands send consumer opt-out requests to Subtotal before turning on event delivery and on an ongoing basis. Opted-out shoppers' data isn't sent to ad platforms.

To see how it works and what setup looks like, start with the Subtotal Signal docs.