Walking into the right store doesn’t guarantee the right products and ingredients end up in your cart.

Every store carries thousands of options. Some are fresh. Some are overpriced. Some are exactly what you need for dinner.

Programmatic buying works the same way.

Even after selecting the right SSPs and optimizing your supply paths, each supplier still has millions of impressions to choose from. The real question isn’t simply, “which supplier should I buy from?”  It’s, “which impressions should that supplier deliver to me?”

Historically, SSPs have largely acted as distributors of inventory while DSPs decide what to buy after bid requests arrive. Buyers optimize campaigns after impressions have already been purchased.

Buying impressions is considerably more complicated than shopping for groceries:

First, buyers don’t see everything that’s available. Some of the best inventory may never even make it onto the shelf. Because DSPs throttle bid requests, a significant portion of available impressions never reaches the buyer for evaluation. 

Second, much of what buyers do see isn’t relevant to their campaign goals. Imagine having to evaluate every product in the store, even when you have a shopping list and know what you want. Performance insights generated in DSPs and attribution partners rarely flow back upstream to SSPs, so buyers repeatedly evaluate large volumes of impressions that have little chance of driving results.

Finally, buyers can unknowingly bid against themselves. The same impression often travels through multiple supply paths, creating duplicate bidding opportunities that inflate prices without increasing value.

SPO helps simplify the supply chain and reduce much of this inefficiency, but brands must go a step further to ensure the right impressions are delivered in the first place, reducing duplication, filtering low-value inventory and continuously learning which impressions are most likely to perform.