The Hidden Threat Draining Your Marketplace Revenue

If you're running Google Ads while also selling on Amazon, Etsy, or eBay, you face a unique challenge that most PPC guides completely overlook: your own advertising campaigns might be stealing traffic from your marketplace stores. This phenomenon, called traffic cannibalization, occurs when your Google Ads campaigns inadvertently compete with your organic marketplace presence, forcing you to pay twice for the same customer.

The math is brutal. When a potential customer searches for your products on Google, they might click your paid ad instead of finding your Amazon listing organically. Now you're paying Google's cost-per-click plus Amazon's 15% referral fee, when that customer might have found you on Amazon anyway. For marketplace sellers operating on razor-thin margins, this double taxation can turn profitable products into money pits. According to research on Amazon ad cannibalization, sellers often experience substantial overlap between their paid traffic sources without realizing the true cost.

The solution isn't to abandon Google Ads. It's to implement a strategic negative keyword framework that prevents your campaigns from competing with your marketplace presence while still capturing valuable traffic that wouldn't find you otherwise. This guide shows you exactly how to build that framework.

Understanding Traffic Cannibalization: Why Marketplace Sellers Pay Double

Traffic cannibalization happens when multiple marketing channels compete for the same customer at the same moment. For marketplace sellers, this typically manifests in three ways.

Direct Product Cannibalization

When your Google Ads appear for searches that would have led to your Amazon, Etsy, or eBay listings organically, you're paying for traffic you would have received for free. A customer searching for handmade leather wallet might see both your Google Shopping ad and your Etsy listing. If they click your ad first, you pay Google's CPC. If they later purchase on Etsy, you also pay Etsy's transaction fee.

This dual cost structure devastates margins. Consider a product with a $50 sale price and $20 cost of goods. After Etsy's 6.5% transaction fee and 3% payment processing fee, you net $45.25. If you also paid $3 for the Google Ads click that drove that customer, your actual margin drops from $25.25 to $22.25 - an 11.8% reduction in profitability from a single cannibalization event.

Brand Name Cannibalization

Customers who already know your brand and search for it by name represent your most valuable traffic. These are high-intent users actively seeking your products. When your Google Ads capture these branded searches, you're paying for traffic that would have found your marketplace stores through organic search results.

If your brand is SilverCraft Jewelry and someone searches SilverCraft Jewelry Etsy, they're explicitly looking for your Etsy store. A Google Ad intercepting this search wastes budget on a customer who was already on their way to you. Even worse, many marketplace platforms rank established sellers prominently for branded searches, meaning your organic visibility for these terms is often excellent.

Marketplace Comparison Cannibalization

Searchers often include marketplace names in their queries when comparison shopping, using searches like best price for kitchen mixer Amazon or vintage posters eBay. These users have already decided to shop on a specific marketplace. Your Google Ads competing for these searches creates an expensive detour that rarely changes their destination.

Data from eBay's 2025 marketplace statistics shows that nearly half of eBay's 2.4 billion listings were active promoted listings, demonstrating that sellers are already paying for visibility within marketplaces. Adding Google Ads costs on top creates a compounding expense structure that quickly becomes unsustainable.

The Marketplace Protection Framework: Strategic Negative Keywords That Stop Cannibalization

Building a negative keyword strategy for marketplace sellers requires a different approach than standard PPC management. You need to identify and exclude searches that indicate marketplace intent while preserving traffic for direct-to-consumer opportunities. This framework organizes negative keywords into five strategic categories.

Category One: Marketplace Name Negatives

The most fundamental layer of protection involves excluding any search that includes marketplace names. These searchers have already chosen their shopping platform, and intercepting them wastes budget while providing minimal value.

Add these as broad match negative keywords across all campaigns:

• amazon
• etsy
• ebay
• marketplace
• seller
• shop (when combined with marketplace terms)

The broad match type ensures variations like amazone, etsey, or e bay are also excluded. This protects against misspellings while maintaining simplicity. You can learn more about the strategic impact of negative keywords in our guide on how to quantify the true impact of negative keywords on ROAS.

Category Two: Comparison Shopping Negatives

Searchers using comparison-oriented language are typically in research mode and have low immediate purchase intent. More importantly, they often plan to complete their purchase on a marketplace where they can compare multiple sellers.

Exclude these comparison-focused terms:

• vs
• versus
• compare
• comparison
• best price
• cheapest
• lowest price
• reviews (when seeking marketplace seller reviews)

These exclusions serve dual purposes. They prevent cannibalization of marketplace traffic where your products appear in comparison results, and they filter out low-intent traffic that rarely converts at profitable rates. For e-commerce sellers managing inventory across channels, real-time negative keyword triggers when products go out of stock become equally important.

Category Three: Account-Specific Negatives

Customers searching for account management terms are existing marketplace users, not new customer prospects. These searches indicate a user trying to access their account, track orders, or manage their marketplace activity.

Block these account-related searches:

• login
• sign in
• account
• my orders
• track order
• customer service
• return policy (when combined with marketplace names)

These searches have zero commercial value for new customer acquisition. A user searching amazon account login is not a purchase prospect, they're an existing Amazon customer managing their account.

Category Four: Reseller and Arbitrage Negatives

A substantial portion of marketplace searches come from other sellers researching products, prices, and competition. These searches represent zero customer value and can drain budgets quickly if left unchecked.

Exclude these reseller-focused terms:

• dropship
• dropshipping
• wholesale
• bulk
• resale
• arbitrage
• supplier
• alibaba

This category becomes especially important for print-on-demand and dropshipping sellers who face unique challenges. Our analysis in The Print-on-Demand and Dropshipping PPC Nightmare reveals how negative keywords separate profitable products from margin destroyers.

Category Five: Informational Intent Negatives

Marketplace searchers often seek information about how platforms work, seller requirements, fee structures, and policies rather than products to purchase. These informational searches carry no purchase intent.

Block these informational queries:

• how to sell
• seller fees
• become a seller
• seller requirements
• commission
• how much does it cost to sell
• tutorial

According to research from Shopify on identifying and fixing keyword cannibalization, informational searches can consume 20-30% of e-commerce PPC budgets when left unmanaged, with conversion rates near zero.

Advanced Implementation: Platform-Specific Negative Keyword Strategies

While the five core categories provide foundational protection, each marketplace platform has unique characteristics that require tailored negative keyword approaches.

Amazon-Specific Protection Strategy

Amazon's dominant market position means searchers frequently use Amazon-specific terminology that you need to exclude. Amazon also runs extensive Google Ads campaigns, creating additional cannibalization risks.

Add these Amazon-specific negative keywords:

• prime
• prime day
• fba
• fulfilled by amazon
• amazon basics
• amazon's choice
• subscribe and save

The prime exclusion deserves special attention. While it eliminates searches like wireless headphones amazon prime, you should monitor for false positives if you sell products where 'prime' has alternative meanings (prime lenses for photography, prime numbers for educational products, prime rib for food sellers).

Amazon's advertising generated significant revenue in 2025, and their Google Ads presence means your ads often compete directly with Amazon's own promotional campaigns. This creates a scenario where you pay Google to compete with Amazon's ads, then pay Amazon fees if the customer ultimately purchases on their platform.

Etsy-Specific Protection Strategy

Etsy attracts searchers looking for handmade, vintage, and unique items. The platform's brand is strongly associated with these product characteristics, creating unique search patterns you need to address.

Implement these Etsy-focused exclusions:

• handmade on etsy
• etsy shop
• etsy seller
• craft marketplace
• artisan marketplace
• custom order etsy

Etsy searchers often use highly specific combined queries like personalized wooden signs etsy or vintage 1970s poster etsy. These represent customers who have already decided Etsy is their preferred shopping platform, making them poor targets for external advertising.

With Etsy's seller tools including advertising, payment processing, and shipping fees comprising 28% of the platform's revenue, sellers already face substantial built-in costs. Adding Google Ads expenses on top of Etsy's fee structure requires careful cannibalization management to maintain profitability.

eBay-Specific Protection Strategy

eBay's auction format and focus on deals attract a distinct searcher mindset. Users often include eBay in searches specifically to find auction opportunities, used items, or discounted merchandise.

Exclude these eBay-characteristic searches:

• auction
• bid
• bidding
• buy it now
• ebay deals
• used [product] ebay
• refurbished ebay

The auction-focused terms are particularly important. A searcher looking for vintage watch auction wants the bidding experience, not a fixed-price purchase. Your Google Ads can't compete with that intent, making these searches waste spending opportunities.

eBay's promoted listings program reached impressive scale in 2025, with nearly half of the platform's 2.4 billion listings actively promoted. This means eBay sellers already invest heavily in on-platform visibility, making external advertising overlap particularly expensive.

Cross-Platform Negative Keyword Lists: Efficiency Through Centralization

If you sell on multiple marketplaces simultaneously, you face amplified cannibalization risks. A customer might find you on Amazon, Etsy, and eBay for the same search, and your Google Ads competing with all three creates triple cannibalization exposure.

Building a Shared Negative Keyword List

Google Ads allows you to create negative keyword lists that apply across multiple campaigns. For marketplace sellers, this centralized approach ensures consistent protection and simplifies management. According to Google's official documentation on negative keyword lists, you can create lists with up to 5,000 negative keywords and apply them to multiple campaigns simultaneously.

Create a master negative keyword list named Marketplace Protection that includes all marketplace names, comparison terms, and platform-specific keywords. Apply this list to every campaign in your account to ensure universal protection.

This centralized approach delivers three key advantages. First, it prevents gaps in coverage where some campaigns accidentally target marketplace searches. Second, it simplifies updates when you need to add new negative keywords. Third, it creates consistency across your account, making audits and optimization easier.

Campaign-Specific Customization

While shared lists provide baseline protection, individual campaigns may need additional negative keywords based on product category, target audience, or competitive landscape.

For example, a jewelry seller might add wholesale jewelry supplies and jewelry making components to campaigns for finished products, while a home goods seller might exclude diy and how to make.

Regular search term report analysis reveals campaign-specific cannibalization patterns. Review these reports weekly during the first month, then bi-weekly thereafter. Look for any searches containing marketplace names, comparison language, or reseller intent that slipped through your initial negative keyword framework.

Monitoring and Optimization: Protecting Against Evolving Cannibalization Patterns

Marketplace cannibalization isn't a one-time fix. Search behavior evolves, new platforms emerge, and marketplace features change. Your negative keyword strategy must adapt continuously.

Search Term Report Analysis Protocol

Your search term reports contain the evidence of cannibalization attempts. Analyzing them systematically reveals exactly where your budget is leaking to marketplace-intent searches.

Export your search term report weekly and sort by cost. Focus on the top 100 highest-cost search terms. For each term, ask three questions:

• Does this search include a marketplace name or obvious marketplace intent?
• Would this searcher likely find our marketplace stores organically?
• Does this search indicate comparison shopping rather than direct purchase intent?

If you answer yes to any question, add that term as a negative keyword. Use phrase match for multi-word terms and exact match for precise exclusions. This systematic approach catches cannibalization patterns before they drain significant budget.

Tools like Negator.io automate this analysis by using AI to identify marketplace-intent searches based on context. Instead of manually reviewing hundreds of search terms, AI-powered classification flags cannibalization risks automatically, saving 10+ hours per week while improving accuracy. The platform's protected keywords feature also prevents accidentally blocking valuable marketplace-adjacent searches that still represent direct customer intent.

Key Performance Indicators for Cannibalization Management

Standard PPC metrics don't directly measure cannibalization. You need specialized KPIs that reveal the true impact of marketplace traffic overlap.

Track cannibalization rate by calculating the percentage of search terms that include marketplace keywords or intent signals. A healthy account should show less than 2% cannibalization rate. If yours exceeds 5%, you're wasting substantial budget on marketplace-directed traffic.

Monitor dual attribution occurrences where customers click your Google Ad but purchase through a marketplace. This requires matching email addresses or customer IDs across platforms. When dual attribution exceeds 15% of conversions, cannibalization is materially impacting your economics.

Calculate marginal ROI including marketplace fees. For Google Ads conversions that also incurred marketplace fees, your true ROI is net of both costs. If a $100 product sale came from a $5 Google Ads click and a $15 Amazon referral fee, your acquisition cost is $20, not $5. Tracking marginal ROI reveals the real profitability of your paid traffic.

Strategic Exceptions: When Marketplace Advertising Makes Sense

While cannibalization protection is critical, absolute rules create missed opportunities. Three scenarios justify intentionally advertising to marketplace-directed traffic.

New Product Launches

When launching new products, your marketplace stores lack reviews, sales history, and ranking signals. During this vulnerable period, Google Ads can drive initial traffic that kickstarts marketplace momentum. For detailed guidance, see our 30 days of negative keyword prep before a major e-commerce product drop.

For the first 30 days after launching on Amazon, Etsy, or eBay, temporarily pause your marketplace name exclusions for campaigns promoting that specific product. This allows your Google Ads to compete with marketplace results, driving traffic that generates the initial reviews and sales velocity needed for organic ranking.

After 30 days, or once you've achieved 10+ reviews and consistent sales, reinstate the marketplace negative keywords. At that point, your organic marketplace visibility should be established, making continued paid cannibalization wasteful.

Competitive Conquest

If competitors dominate marketplace search results for valuable terms, Google Ads provides an alternative visibility path. This works best for established brands with loyal customers who might comparison shop on marketplaces but ultimately prefer purchasing directly.

A premium kitchen goods brand competing against cheaper alternatives on Amazon might strategically advertise on searches like best stand mixer amazon. The goal isn't to win the Amazon sale, it's to intercept comparison shoppers and redirect them to your direct-to-consumer channel where margins are higher.

This strategy only works if your direct channel conversion rate exceeds your marketplace conversion rate by enough to offset the additional advertising cost. Measure incrementality by comparing direct sales during competitive conquest campaigns versus baseline.

Inventory or Pricing Advantages

When you have inventory, variants, or pricing your marketplace stores don't offer, Google Ads can capture marketplace-directed traffic without true cannibalization. This occurs most commonly with custom configurations, bulk options, or seasonal specials.

A furniture seller might offer standard items on Amazon but custom sizing on their direct site. Advertising to custom desk Amazon captures searchers who won't find that option on your marketplace store, making the traffic incremental rather than cannibalistic.

Implementation Checklist: Your 7-Day Marketplace Protection Setup

Implementing comprehensive marketplace cannibalization protection requires systematic execution. Follow this seven-day implementation plan to build complete coverage efficiently.

Day One: Account Audit

Export your last 90 days of search term data. Filter for terms containing marketplace names and calculate total cost. This baseline measurement shows exactly how much budget currently leaks to cannibalization.

Day Two: Build Core Negative Keyword List

Create your master negative keyword list including all marketplace names, comparison terms, account-related searches, reseller keywords, and informational queries. This should total 50-100 negative keywords covering the five core categories.

Day Three: Add Platform-Specific Negatives

Customize your list with platform-specific terms for Amazon, Etsy, and eBay based on which marketplaces you actively use. This adds another 20-40 negative keywords tailored to your specific multichannel presence.

Day Four: Apply Lists to Campaigns

Apply your master negative keyword list to all active campaigns. Verify application by checking each campaign's negative keywords section and confirming the list appears.

Day Five: Configure Shopping Campaign Protection

Shopping campaigns require special handling because they don't target keywords. Add your marketplace negative keywords at the campaign level, using broad match to ensure maximum coverage against triggering on marketplace-directed searches.

Day Six: Set Up Monitoring Protocols

Create saved reports in Google Ads that automatically filter search terms containing marketplace keywords. Schedule weekly exports to catch any new cannibalization patterns that emerge.

Day Seven: Establish Baseline Metrics

Record your current ROAS, average CPC, and conversion rate. These pre-implementation baselines allow you to measure the impact of your cannibalization protection over the next 30 days. Most sellers see 15-25% ROAS improvement within the first month as wasted spend gets eliminated.

Conclusion: Protecting Margins While Scaling Multi-Channel Presence

Marketplace cannibalization represents one of the most expensive blind spots in e-commerce PPC management. Every dollar spent advertising to customers who would have found your Amazon, Etsy, or eBay stores organically is a dollar of pure waste that directly erodes your profit margins.

The negative keyword framework outlined in this guide provides systematic protection against this hidden cost. By implementing the five core categories of marketplace-focused negative keywords, adding platform-specific exclusions, and maintaining ongoing monitoring through search term analysis, you ensure your Google Ads budget focuses exclusively on incremental customer acquisition.

The impact is immediate and measurable. Within days of implementation, you'll see marketplace-directed searches disappear from your search term reports. Within weeks, your ROAS improves as the same budget generates more profitable conversions. Within months, the compounding effect of cleaner traffic and better data creates a sustainable competitive advantage.

For marketplace sellers operating on thin margins, this isn't optional optimization. It's essential survival strategy. Your competition is already paying double for cannibalized traffic. Don't join them. Implement marketplace protection negative keywords today and keep your hard-earned margins where they belong - in your pocket, not leaked to unnecessary advertising costs.

The tools and frameworks exist to automate this protection. AI-powered platforms like Negator.io analyze search terms in context, automatically flagging marketplace-directed searches while protecting valuable traffic. What once required hours of manual analysis now happens automatically, giving you the control and efficiency needed to scale profitably across multiple channels.

Stop paying twice for the same customer. Implement strategic negative keywords and protect your marketplace traffic from cannibalization starting today.