Ad exchange

In programmatic advertising, an ad exchange is a digital marketplace where online ad space is bought and sold. It enables advertisers to bid on inventory from multiple publishers in real-time, ensuring their ads are displayed to a relevant audience. 

What is an ad exchange?

What is an ad exchange? Glossary video

An ad exchange is an online platform for buying and selling advertising inventory across websites, mobile sites, and mobile apps. 

In the programmatic advertising ecosystem (where digital ad space is bought and sold automatically and in real-time), ad exchanges are a digital marketplace that connects advertisers (the demand/buy side) with publishers (the supply/sell side). 

What is an ad exchange

Examples of ad exchanges

There’s a range of ad exchanges to choose from (scroll down to “How to choose an ad exchange section” to pick the right one for you).

Some popular ones include:

  • Google AdX
  • Xandr
  • Magnite
  • Open X
  • PubMatic
  • Smartyads
  • Smaato

Ad exchange vs ad network

You’ll also come across the term “ad network”. While this might sound similar to an ad exchange, it’s important not to confuse the two. 

Ad exchange vs ad network

An ad exchange is essentially a trading platform, whereas an ad network acts as an intermediary: it aggregates ad supply from publishers, and matches it with advertiser demand. It does this by collecting inventory from a list of publishers, or buying impressions in bulk from an ad exchange. It then sorts them and resells the space to advertisers — saving them time and resources. 

Benefits of using an ad exchanges

Ad exchanges make the process of buying and selling media more efficient and transparent for both advertisers and publishers. Here are their main advantages: 

Ad exchange benefits for advertisers

  • Targeting: Ad exchanges use sophisticated algorithms that enable advertisers to reach highly specific audiences, showing them the most relevant message at exactly the right time. 
  • Rapid reach: Exchanges enable advertisers to easily buy ads across a range of sites and apps at once, rather than negotiating with individual publishers.
  • Control: Advertisers have full control over where their ads are placed, ensuring brand safety. 
  • Transparent costs: Ad exchanges often operate on a cost per mille (CPM) model, where advertisers pay a fixed price for 1,000 impressions of their ad. 

Ad exchange benefits for publishers

  • Revenue: The transparent bidding process helps publishers get the best price for their ad real estate, and they can also set a minimum price. 
  • Brand safety: Just like the advertisers, publishers have control over which ads they choose to display, ensuring a good brand fit for their users.  
  • Format: Publishers control the format of ads, so they fit in with the overall site or app design. 

How do ad exchanges work?

An ad exchange lets advertisers bid on inventory across a wide pool of publishers.

Publishers use software called a supply-side platform (SSP) to make impressions available for auction. On the other side, advertisers and agencies use a demand-side platform (DSP) to buy inventory automatically. 

The SSP and DSP connect to the ad exchange, where the real-time bidding process takes place.  

What actually happens during real-time bidding (RTB)

Ad exchange and real time bidding

RTB is based on a fully automated process that calculates the price of the advertising space and inventory in real-time, depending on supply and demand factors. Advertisers can bid on ad space with a specific number of ad impressions, and the winning ad is displayed to the user. .

Here’s how this works in practice:

  1. The moment a user lands on a web or in-app page, an ad impression is triggered for auction on the exchange, via the publisher’s SSP. 
  2. The advertiser’s DSP can analyze data from multiple sources – such as the user’s mobile identifier (if they’ve given consent), time of day, device type, ad position, demographics, and purchasing behavior – to figure out whether to bid on the impression, and how much.
  3. Within a fraction of a second, the winning bidder is selected and the publisher instantly serves up the ad to the user.

Types of exchanges

Advertisers and publishers can choose from three main types of ad exchange, depending on their goals and expectations.

Types of ad exchanges

1. Open ad exchange

Also known as a public marketplace or an open auction, an open ad exchange is a digital marketplace that’s open to everyone. The breadth of publishers on open exchanges makes them best suited to advertisers looking for wide reach. 

On the downside, advertisers don’t have detailed information about the publishers. Ad fraud is also a concern, given the tens of billions of impressions flowing through open ad exchanges every day. For these reasons, some advertisers prefer the security of a private ad exchange.

2. Private ad exchange 

A private ad exchange, or private marketplace (PMP), is a closed, “premium” platform that enables the publisher to control which advertisers can bid, at what price and under which conditions. Each one is run by an individual publisher that personally invites selected advertisers. 

A private ad exchange allows brands and publishers to set up direct relationships with advertisers and agencies, so negotiations may take longer than on an open ad exchange. 

3. Preferred deal

A preferred deal allows publishers to sell digital ad inventory to selected advertisers at a negotiated fixed price. This gives the publisher a stable revenue stream through a controlled transaction system, while advertisers benefit from stable CPM prices and access to an exclusive inventory.

Mobile ad exchanges

A mobile ad exchange is simply one that specializes in mobile advertising, enabling advertisers to buy space within apps rather than on websites. The detailed and specific data available from apps means these exchanges can offer sophisticated targeting based on app user behavior.

How to choose an ad exchange

How to choose an ad exchange

We’ve covered the main types of ad exchange, but how do you narrow it down to find the right one for you? Here are some factors to consider: 


An exchange that provides access to a broad pool of publishers offers advertisers greater campaign reach. At the same time, having more advertisers on board gives publishers a wider choice of relevant brands for their audience. 

Targeting capabilities 

Different ad exchanges offer varying levels of segmentation and targeting, enabling audiences to be grouped by demographics, location, behavioral patterns, and more. 

Advertisers should make sure they can reach their specific audience, while publishers will want to know they’re serving relevant and appropriate ads to their users. 

Ad formats supported

Display ads, video ads, native ads… Digital ads come in many shapes and sizes, but not all formats are available on every ad exchange. More formats means greater creative choice and control for advertisers, and more monetization opportunities for publishers. 

Data analytics

The more campaign data your ad exchange can provide, the better. Real-time insights help both advertisers and publishers to optimize ad placement and engagement, benefiting their bottom line. (It goes without saying that your exchange must comply with all data privacy rules.)

Fraud protection

The vast networks and automated nature of ad exchanges mean fraud is all too common — hurting both budgets and reputations. A reputable exchange will take steps to protect both advertisers and publishers, such as quality-checking ads, ensuring clicks are attributed correctly, and blocking potentially risky suppliers. 

Ad exchanges are here to stay, but how might they evolve? Here are a few trends to watch:

AI driving improvements

As with most areas of digital marketing, artificial intelligence is revolutionizing how ad exchanges work. AI can analyze vast amounts of data in real time, facilitating improved targeting and instant campaign optimization. And machine learning capabilities can help predict campaign success and even highlight fraudulent behavior.

Privacy first

Ad exchanges depend on user and behavioral data to get relevant ads in front of the right audiences. But that data is getting harder to come by, with Google preparing to phase out third-party cookies and Apple already requiring user consent to share device IDs. To stay compliant, exchanges will need to be smart about what data they collect and how.  

Spotlight on CTV

Connected TV is one of the fastest-growing platforms for programmatic advertising. The rise of streaming offers advertisers an unprecedented opportunity to reach an engaged and highly targeted audience. As demand continues to grow, we can expect to see more ad exchanges offering specialist CTV services.  

Optimize your ad exchange activities with mobile attribution

Attribution data gives online advertisers valuable insights into the effectiveness of their ad exchange buys. Identifying your most and least valuable digital investments empowers you to make smarter budget decisions, and optimize your campaign performance, ROAS, and LTV

With an ad exchange, you get real-time campaign data so you can take swift action to improve results. 

Frequently asked questions

What is an ad exchange? 

An ad exchange is a digital marketplace where advertising inventory is bought and sold in real-time across websites, mobile sites, and apps. It facilitates programmatic advertising by connecting publishers with advertisers, streamlining the bidding process.

What’s the difference between an ad exchange and an ad network? 

Ad exchanges and ad networks both connect advertisers with publishers. The difference is that ad exchanges provide an open, real-time bidding platform for ad space, whereas ad networks act as intermediaries, aggregating ad spaces from publishers and selling them to advertisers. An exchange is an open pool of impressions, while a network is a closed group. 

What are the benefits of using ad exchanges? 

Ad exchanges offer advertisers precisely targeted, efficient ad buys across multiple sites at once, with full control over ad placements. Publishers can control which ads to display and how, while transparent pricing helps both parties maximize profits.

How do ad exchanges work? 

Ad exchanges work like auctions, using DSPs (demand-side platforms) to enable advertisers to bid on ad spaces in real-time as users visit websites or apps. The highest bidder wins the ad spot, allowing for precise targeting and immediate ad placement.

What are the main types of ad exchanges available? 

There are three main types: open ad exchanges offer extensive publisher inventory to all advertisers; private ad exchanges allow publishers to control who bids on their inventory; preferred deals enable direct negotiations for ad inventory at fixed prices. Open exchanges offer the broadest reach, whereas the others provide a more premium service.

What is a mobile ad exchange?

A mobile ad exchange is one tailored to the mobile environment. It enables advertisers to buy space within mobile apps, drawing on behavioral data for sophisticated targeting.

How should I choose the right ad exchange?

Consider factors like the reach and variety of publishers on the exchange, targeting capabilities, supported ad formats, access to data analytics for optimization, and measures for fraud protection to choose the most suitable ad exchange for your needs.

Key takeaways

Ad exchanges sit at the heart of the programmatic advertising ecosystem. Here are the key points to remember about them:

  1. An ad exchange is a platform that connects online advertisers with publishers. It acts as an online marketplace where digital ad inventory is bought and sold automatically and in real-time. 
  2. While an ad exchange is an open pool of impressions, an ad network aggregates impressions from multiple publishers and sells them on to advertisers. 
  3. For advertisers, the benefits of using an ad exchange include wide reach, sophisticated targeting, control, and transparent costs. Publishers get the best price in a transparent way, and can control which ads to show and in what format. 
  4. Advertisers and publishers connect to an ad exchange using a demand-side platform and a supply-side platform, respectively. This enables advertisers to bid on relevant space in real-time, with the winning ad served to the user in a fraction of a second. 
  5. The main types of ad exchange are open, private, and preferred deal. While open markets offer the widest reach, private and preferred options offer greater control and exclusivity. 
  6. Mobile ad exchanges specialize in inventory within mobile apps, and offer sophisticated targeting based on app user behavior. 
  7. When choosing an ad exchange, you should consider and compare reach, targeting, ad types supported, data analytics, and fraud protection. 
  8. Attribution can help you optimize exchange activity by identifying your most and least valuable ad investments.
  9. Future trends for ad exchanges include the development of AI and machine learning, tighter privacy regulations, and the rise of CTV.
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