Costco
RetailFameproof index
78.6−0.2
Costco
Retail average
Claude 4.5
−0.6
77.5
Mention rate78%
Avg. position2.3
Factual accuracy92%
SentimentPositive
ChatGPT (GPT-5)
−0.2
78.7
Mention rate75%
Avg. position1.9
Factual accuracy94%
SentimentPositive
Gemini 2.5
+0.1
79.5
Mention rate79%
Avg. position1.9
Factual accuracy92%
SentimentPositive
Prompt performance
Position when mentioned · 1,200 promptsPrompt
CL
GPT
GEM
“Cheapest supermarket for a weekly shop”
#1
#2
#2
“Best retailer for household basics”
—
#4
#1
“Which chain has the best own-brand range”
—
#3
—
“Where to buy groceries online”
#3
#1
#2
“Best value big-box retailer”
—
#1
#3
A 5-prompt sample of the 1,200-prompt weekly panel.
Who wins the prompts Costco loses
Most-cited sources
What the models lean on when they describe Costco.
docs.costco.comwikipedia.orgg2.comnews.ycombinator.comreddit.com/r/business
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