How private marketplaces work in programmatic advertising

How private marketplaces work in programmatic advertising

Private marketplaces give advertisers controlled access to publisher inventory through programmatic technology.

They sit between open auction buying and traditional direct media deals.

A private marketplace can offer greater transparency, stronger publisher relationships, more consistent inventory quality, and clearer commercial terms. But a PMP does not automatically guarantee premium performance.

The outcome depends on how the deal is structured, priced, activated, and monitored.

This guide explains how private marketplace deals work, including deal IDs, price floors, inventory priority, buyer and seller responsibilities, and the most common reasons PMP campaigns fail to deliver.

What is a private marketplace?

A private marketplace, commonly called a PMP, is a restricted programmatic buying environment where a publisher makes selected inventory available to approved buyers.

Unlike the open auction, access is limited.

The publisher may invite:

• A specific advertiser
• An agency
• A trading desk
• A DSP seat
• A selected group of buyers

The transaction still uses programmatic technology, but the buyer and seller agree on certain conditions before activation.

These conditions may include:

• Inventory type
• Ad format
• Geographic market
• Device
• Audience
• Price
• Deal duration
• Buyer seat
• Creative requirements

Private marketplace deals are generally non-guaranteed. The buyer receives access to eligible inventory, but neither side is necessarily committed to a fixed volume of impressions. Google Ad Manager classifies Preferred Deals and Private Auctions as non-guaranteed PMP deal types.

Why advertisers use private marketplaces

Advertisers typically use PMPs when they want more control than the open auction provides.

A PMP may help a buyer access:

• Selected publisher inventory
• Premium page or app placements
• Connected TV inventory
• High-viewability ad units
• Publisher-defined audience segments
• Brand-suitable environments
• Inventory that is not broadly available through the open market

The main value is not simply exclusivity.

It is the ability to create a more deliberate connection between an advertiser, a publisher, and a defined inventory package.

Why publishers use private marketplaces

Publishers use PMPs to create stronger commercial relationships with advertisers while maintaining programmatic efficiency.

A publisher may use a PMP to:

• Control which buyers access selected inventory
• Protect the value of premium placements
• Set pricing expectations
• Package specific audiences or content
• Improve demand quality
• Reduce reliance on the open auction
• Build direct relationships with agencies and brands

PMPs allow publishers to retain more control over how their inventory is sold without returning to a completely manual insertion-order process.

How a private marketplace deal is created

A PMP begins on the supply side.

The publisher or seller creates the deal through a supply-side platform or publisher ad server.

The deal usually includes:

• Deal name
• Deal ID
• Buyer or DSP seat
• Inventory selection
• Ad format
• Floor or fixed price
• Start and end dates
• Geographic targeting
• Device eligibility
• Creative requirements

The buyer then receives the deal details and activates the inventory within its demand-side platform.

The typical PMP workflow

A private marketplace deal usually follows this process:

1. The buyer and publisher discuss campaign requirements
2. The publisher creates the deal in its selling platform
3. The platform generates a deal ID
4. The publisher shares or syncs the deal with the buyer
5. The buyer accepts the deal in the DSP
6. The buyer assigns the deal to a campaign or line item
7. Eligible bid requests include the deal information
8. The DSP evaluates the opportunity and submits a bid
9. The publisher selects the winning eligible demand
10. Both parties monitor delivery and performance

The exact steps vary by DSP, SSP, exchange, and publisher setup.

What is a deal ID?

A deal ID is a unique identifier used to connect the agreed deal terms across the publisher’s selling platform and the advertiser’s buying platform.

In simple terms, it tells the systems:

This bid is being submitted under a specific commercial agreement.

When a bid is made under a private marketplace agreement, the bid can include the ID of the relevant deal object. This is part of the OpenRTB framework used across programmatic transactions.

What a deal ID does

A deal ID can help identify:

• The publisher
• The approved buyer
• The eligible inventory
• The pricing model
• The agreed format
• The deal dates
• The relevant auction rules

It does not contain all these details in a form that the campaign manager directly reads.

Instead, it links the buyer’s bid to the deal terms configured in the participating platforms.

What a deal ID does not guarantee

Receiving a deal ID does not guarantee that the campaign will spend.

A deal may still underdeliver because:

• The buyer is using the wrong DSP seat
• The bid is below the price floor
• The creative format is not eligible
• The campaign targeting does not match the deal
• The deal is inactive
• The publisher has limited available inventory
• Higher-priority demand wins
• The creative has not been approved
• The buyer has not correctly assigned the deal

A deal ID provides access. It does not guarantee delivery.

Private auction vs preferred deal

Private marketplace is a broad term that can include different non-guaranteed buying arrangements.

Two common types are private auctions and preferred deals.

Private auction

A private auction allows selected buyers to compete for eligible inventory.

The publisher sets a minimum price, commonly called a floor.

Buyers can bid above that floor, and the impression is allocated according to the publisher’s auction and priority rules.

A private auction typically includes:

• Restricted buyer access
• A floor CPM
• Multiple possible buyers
• Non-guaranteed delivery
• Auction-based pricing

Preferred deal

A preferred deal generally gives a selected buyer the first opportunity to purchase eligible inventory at an agreed fixed CPM.

The buyer is not obligated to purchase every impression, and the publisher does not necessarily guarantee volume.

A preferred deal usually includes:

• A specific buyer
• A fixed CPM
• Non-guaranteed volume
• Defined inventory
• Higher access priority than a standard private auction in some publisher systems

In Google Ad Manager, Preferred Deals use a fixed price, while Private Auctions use a floor price. Google also notes that Preferred Deals are typically prioritized above Private Auctions and the Open Auction, although actual serving can depend on the publisher’s configuration and dynamic allocation rules.

PMP vs programmatic guaranteed

Private marketplace and programmatic guaranteed deals are not the same.

Private marketplace

A typical PMP is:

• Non-guaranteed
• Auction-based or fixed-price
• Dependent on inventory availability
• Flexible for the buyer
• Not committed to a fixed impression volume

Programmatic guaranteed

A programmatic guaranteed deal usually includes:

• Reserved inventory
• Agreed impression volume
• Fixed pricing
• Defined campaign dates
• A direct commitment between buyer and seller

Programmatic guaranteed buying provides more delivery certainty, while PMPs provide more flexibility.

Understanding price floors

A price floor is the minimum bid the publisher is willing to accept for eligible inventory.

For example, if a private auction has a $12 CPM floor:

• A $9 CPM bid is not eligible to win
• A $12 CPM bid may be eligible
• A $15 CPM bid may be more competitive

The actual outcome still depends on other eligible demand and the publisher’s auction setup.

In DV360, non-guaranteed inventory can be configured with either a fixed CPM or a floor CPM, depending on whether the inventory source is a preferred deal or private auction.

Why publishers set price floors

Publishers use floors to:

• Protect premium inventory value
• Avoid selling below an acceptable price
• Differentiate premium inventory from open auction supply
• Maintain commercial consistency
• Control yield

The floor should reflect demand, inventory quality, format, audience, and market conditions.

Why high floors can reduce delivery

A high floor may protect publisher pricing, but it can also limit buyer participation.

The campaign may struggle if:

• The buyer’s bid is close to or below the floor
• The audience is narrow
• The inventory is limited
• Other buyers are bidding more aggressively
• The campaign has strict targeting controls

A deal can be technically active while delivering almost nothing because the commercial terms are not competitive.

Why low floors are not always better

A lower floor may improve scale, but it does not automatically improve quality or performance.

Buyers should evaluate:

• Viewability
• Completion rate
• Audience quality
• Placement
• Conversion rate
• Supply transparency
• Incremental reach

The right floor is the one that creates a workable balance between publisher value and buyer performance.

Inventory priority in private marketplaces

Publishers often have several demand sources competing for the same impression.

These may include:

• Direct guaranteed campaigns
• Programmatic guaranteed deals
• Preferred deals
• Private auctions
• Open auction buyers
• House ads

There is no universal priority order that applies identically across every publisher and technology platform.

Priority may depend on:

• Publisher ad-server configuration
• Deal type
• Revenue
• Dynamic allocation
• Reserved campaign commitments
• Buyer priority
• Auction rules

In Google Ad Manager, publishers can assign priority among non-guaranteed PMP deals. A higher-priority deal may be favoured even when another buyer submits a higher bid.

Why a PMP does not always win before the open auction

It is common to assume that every PMP bid automatically receives first access.

That is not always true.

A private deal may lose because:

• A guaranteed campaign has reserved the impression
• Another PMP has higher priority
• Another eligible deal submits a better bid
• The bid does not clear the floor
• The publisher allows broader price-based competition
• The creative is ineligible

Buyers should confirm how the publisher prioritizes the deal rather than assuming access equals preference.

The buyer’s role in a PMP

The advertiser or agency is responsible for translating the commercial agreement into a working campaign.

The buyer should verify:

• Correct deal ID
• Correct exchange
• Correct DSP seat
• Campaign dates
• Bid and floor alignment
• Supported creative formats
• Geographic and device targeting
• Audience compatibility
• Brand safety controls
• Tracking and measurement

The buyer also needs to monitor whether the deal delivers the expected quality and scale.

The publisher’s role in a PMP

The publisher should ensure that the deal is correctly configured on the supply side.

This includes confirming:

• Buyer identity
• Seat ID
• Inventory package
• Pricing
• Deal dates
• Eligible formats
• Device settings
• Geographic settings
• Inventory availability
• Creative approval requirements

The publisher should also provide enough transparency for the buyer to troubleshoot delivery.

What buyers and sellers negotiate

Private marketplace discussions may cover:

• CPM
• Price floor
• Fixed vs auction pricing
• Inventory volume
• Publisher sections
• Content categories
• Device type
• Geography
• Ad format
• Audience segments
• Viewability expectations
• Brand suitability
• Frequency
• Reporting
• Measurement
• Cancellation terms

The stronger the agreement, the fewer surprises appear after launch.

Common reasons PMP deals underdeliver

PMP underdelivery is often caused by a mismatch between the buyer’s campaign and the publisher’s deal configuration.

Bid below floor

The campaign bid is lower than the publisher’s minimum price.

This is one of the most common causes of zero or low delivery.

Incorrect buyer seat

The deal was created for one DSP seat, but the campaign is running from another.

The seller may not recognize the buyer as eligible.

Targeting mismatch

The deal may support one geography, device, or format while the line item targets another.

For example:

• Deal supports Canada, campaign targets the United States
• Deal supports connected TV, creative is standard display
• Deal supports mobile app inventory, campaign targets desktop web

Unsupported creative

The buyer may upload a creative that does not meet:

• Size requirements
• Duration limits
• Video specifications
• Publisher policies
• Secure-serving requirements
• Approval standards

Deal not active

The deal may be paused, expired, awaiting buyer acceptance, or not fully approved.

Limited inventory

Premium inventory can have limited scale.

Even a correctly configured deal may deliver slowly if the publisher has low available volume.

Competing demand

The buyer may lose to:

• Guaranteed campaigns
• Higher-priority PMP deals
• Better bids
• Other eligible buyers

Excessive campaign restrictions

The buyer may layer additional targeting on top of an already narrow deal.

Combining a PMP with restrictive audiences, devices, geography, frequency, and brand-safety settings can leave very little eligible inventory.

A practical PMP troubleshooting checklist

When a private marketplace deal is not delivering, review the following areas.

Deal status

• Is the deal active?
• Has the buyer accepted it?
• Are the start and end dates correct?
• Has the publisher confirmed activation?

Buyer setup

• Is the correct DSP seat being used?
• Is the deal assigned to the correct line item?
• Is the exchange selected correctly?
• Is the campaign active?

Pricing

• What is the floor or fixed CPM?
• Is the campaign bid high enough?
• Are platform and data fees affecting the effective bid?
• Is the bid competitive against other demand?

Inventory eligibility

• Does the deal support the selected geography?
• Does it support the device?
• Does it support the creative format?
• Is there enough available supply?

Creative status

• Is the creative approved?
• Does it meet publisher specifications?
• Is the click URL valid?
• Are third-party tags supported?

Targeting

• Is additional targeting making the line item too narrow?
• Are audience and content filters compatible?
• Is the frequency cap too restrictive?
• Are brand-safety settings excluding most supply?

Auction results

• Is the campaign submitting bids?
• What is the win rate?
• Is it losing to the floor?
• Is it losing to higher-priority demand?
• Are there creative rejections?

DV360 allows buyers to review deal floor prices, associated line items, impressions, and troubleshooting information when managing non-guaranteed inventory.

How to evaluate PMP performance

A PMP should not be judged only by whether it spends.

The buyer should evaluate:

• CPM
• Win rate
• Fill and delivery
• Viewability
• Video completion rate
• Invalid traffic
• Reach
• Frequency
• Click-through rate
• Conversion rate
• Cost per acquisition
• Return on ad spend
• Incremental reach
• Publisher quality

A premium deal should create a measurable advantage over alternative supply.

Compare the PMP with open auction inventory

Buyers should compare PMP performance against similar open auction inventory.

Useful questions include:

• Does the PMP provide higher viewability?
• Does it create incremental reach?
• Does it reduce invalid traffic?
• Does it improve conversion quality?
• Does it provide access to unavailable inventory?
• Does the higher CPM create better outcomes?
• Is the supply path more direct?

A deal should not be retained simply because it is labelled premium.

Benefits of private marketplaces

When structured correctly, PMPs can offer several advantages.

Better inventory control

Buyers know more about the publisher, format, placement, and environment.

Stronger brand suitability

The advertiser can select inventory that fits its brand and campaign requirements.

Access to premium supply

Some publishers make selected inventory available only through negotiated deals.

Improved transparency

Deal-level reporting can make it easier to understand where and how media is being purchased.

Stronger publisher relationships

PMPs create an opportunity for more direct collaboration between buyers and sellers.

More customized packages

Publishers can package inventory around:

• Audiences
• Content
• Events
• Devices
• Formats
• Markets

Limitations of private marketplaces

PMPs also create trade-offs.

Higher prices

Premium access may come with a higher CPM.

Limited scale

A selected publisher or inventory package may not provide enough volume for the entire campaign.

More operational work

Deal activation requires coordination between sales, publishers, agencies, DSP teams, and ad operations.

No automatic performance guarantee

Premium inventory can still underperform.

Troubleshooting complexity

A problem may exist on the DSP, SSP, exchange, ad server, publisher, or creative side.

Best practices for buyers

Define the reason for using the deal

Use a PMP because it offers a clear inventory, audience, quality, or measurement advantage.

Confirm deal details in writing

Document:

• Deal ID
• Seat
• Floor
• Format
• Geography
• Inventory
• Dates
• Expected scale

Test before scaling

Begin with controlled budgets and compare the deal with other supply.

Avoid unnecessary targeting layers

Do not restrict a carefully curated deal unless the campaign strategy requires it.

Monitor delivery early

Review bidding, wins, losses, and impressions within the first day.

Evaluate business outcomes

Do not judge the deal only by CPM or viewability.

Best practices for publishers

Set realistic pricing

The floor should reflect quality and demand without making the deal commercially unusable.

Package inventory clearly

Buyers should understand exactly what the deal includes.

Confirm buyer eligibility

Verify the buyer’s platform and seat before launch.

Share troubleshooting information

Clear communication can resolve delivery problems quickly.

Review deal performance

A deal that consistently underdelivers may need new pricing, targeting, or inventory terms.

When a PMP is the right choice

A private marketplace may be useful when:

• The advertiser needs a specific publisher
• Inventory quality is a priority
• Brand suitability requires greater control
• The buyer needs connected TV or premium video access
• The publisher offers valuable first-party audiences
• The campaign needs more transparent supply
• Open auction inventory does not provide the required environment

When the open auction may be better

Open auction buying may be more suitable when:

• Scale is the main objective
• The budget is limited
• Broad discovery is useful
• The buyer has strong quality controls
• The campaign needs flexible inventory access
• No publisher-specific advantage is required

A well-managed open auction campaign can outperform a poorly designed PMP.

Final takeaway

Private marketplaces combine programmatic efficiency with more controlled buyer and seller relationships.

The core mechanism is straightforward:

• A publisher creates a deal
• A deal ID connects the commercial terms
• The buyer activates the deal in a DSP
• Eligible impressions are evaluated and bid on
• Pricing, priority, targeting, and inventory availability determine delivery

But successful PMP buying requires more than entering a deal ID.

Buyers must understand the floor price, confirm inventory eligibility, align bids and creatives, monitor auction behaviour, and measure whether the deal delivers a real advantage.

A PMP is not valuable because it is private.

It is valuable when it provides better access, better quality, stronger transparency, or better business results than the available alternatives.