What is the fine-grained topic of the following text: For banks, there is a clear correlation between customer loyalty and profitability: Bain & Company estimates that the top 25 US Retail Banks could achieve cost savings of $11.4 Billion simply by matching the NPS scores of their Dutch counterparts, not to mention the $1 Billion in additional revenues that each point reduction in hidden defection would represent. Only return the topic.
Correlation between customer loyalty and profitability in banking.