Amazon's advertising system is an auction, but not a simple highest-bidder-wins auction. Understanding the mechanics helps explain why some keywords perform well, others get no impressions, and why the same keyword in different campaigns can produce different results.
The Core Formula: Bid × Relevance
Amazon uses a second-price auction modified by relevance. This means:
- You pay $0.01 more than the next highest bidder (adjusted for relevance)
- A highly relevant product can win with a lower bid than an irrelevant one
- Amazon prioritizes showing ads that shoppers are likely to click and buy
What Determines Relevance?
Amazon doesn't publish its exact relevance factors, but based on observed behavior:
Relevance Factors
- Listing content: Title, bullets, description, backend keywords
- Category alignment: Product's browse node relative to search intent
- Historical performance: CTR and CVR for this product on this keyword
- Sales history: Overall sales velocity and conversion patterns
- Customer behavior: What products people buy after searching this term
Why Keywords Get Zero Impressions
This is one of the most common frustrations. There are three main causes:
1. Bid Too Low
Your bid doesn't meet the minimum threshold to enter the auction. Amazon has floor prices that vary by keyword competitiveness.
2. Insufficient Relevance
Your product isn't considered relevant enough for this keyword. Even a high bid won't help if Amazon thinks shoppers won't want your product for this search.
3. Low Search Volume
The keyword simply doesn't get searched often enough to generate measurable impressions. Check Brand Analytics to verify actual search volume before assuming bid or relevance issues.
Diagnosis Approach
First, check if the keyword has meaningful search volume (Brand Analytics). If it does, try increasing your bid significantly (50-100%) for a week. If you still get zero impressions, relevance is likely the issue—review your listing to ensure the keyword is well-represented in your content.
Do Campaigns Compete With Each Other?
Same Keyword in Different Campaigns
Yes, they compete. If you have "yoga mat" as an exact match in Campaign A and phrase match in Campaign B, both can be triggered by the same search. Amazon picks one to show based on a combination of bid and expected performance.
What Happens in the Auction
Amazon evaluates all your eligible ads, picks the one with the best combination of bid and expected performance, and enters that one into the auction. You don't bid against yourself—but you might be surprised which campaign ends up serving.
Do Match Types Compete?
Yes. Exact, phrase, and broad match for the same keyword can all be eligible for the same search query. Common misconceptions:
Myth
Exact match always wins over broad match
Fact
The highest performing combination wins, regardless of match type
Does PPC Affect Organic Ranking?
Indirectly, Yes
PPC doesn't directly boost organic ranking. But PPC drives sales, and sales velocity is a major organic ranking factor. So PPC → Sales → Improved Organic Ranking. The effect is real but indirect.
This is why aggressive PPC during launch makes sense: you're buying the sales velocity that eventually earns organic ranking.
Do Negative Keywords Affect Organic?
No. Adding a keyword as negative in your campaigns only affects paid advertising. It has zero impact on organic search ranking or visibility.
This is a common concern when sellers worry about negating relevant keywords. If a keyword is relevant to your product, negating it in PPC won't hurt organic ranking—it just stops you from paying for ads on that term.
Which Backend Fields Are Indexed?
Amazon indexes these fields for advertising (and organic) purposes:
- Search Terms (Backend Keywords): The most important backend field. 250-byte limit.
- Subject Matter: Often overlooked but indexed
- Target Audience: Limited impact but worth populating
- Intended Use: Category-dependent availability
Are Platinum Keywords Still Indexed?
Platinum Keywords were deprecated years ago. Any content in this field is ignored. Don't waste time populating it.
Minimum and Maximum Bids
Minimum Bid
Amazon's minimum bid is $0.02, but this is rarely practical. Effective minimum bids depend on keyword competitiveness—some keywords require $0.50+ just to enter the auction.
Maximum Bid
The maximum bid is $1,000.00 per click. Very few advertisers ever approach this, but extremely competitive keywords in categories like insurance or legal can see CPCs above $50.
Can I Add ASINs as Negatives?
Yes. You can add competitor ASINs as negative targets in product targeting campaigns. This is useful when:
- You're targeting a category but want to exclude certain products
- A competitor's product consistently drives clicks but no conversions
- You want to avoid appearing on your own product pages
Key Takeaways
- Ad rank = bid × relevance. High bids can't overcome irrelevance.
- Zero impressions usually means low bid, poor relevance, or no search volume
- Your campaigns compete with each other—Amazon picks the best one to enter the auction
- PPC affects organic ranking indirectly through sales velocity
- Negative keywords only affect PPC, not organic ranking
- Backend search terms are indexed; Platinum Keywords are not
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