A handful of customers fund the bank. A long tail quietly drains it.
Rank banking customers by true profit and the curve is steep. A minority carry the institution, and once cost to serve is fully loaded, 30 percent or more of relationships turn out to destroy value. A blended cost rate cannot see any of it, because the profitable customers and the loss-making ones are averaged into one number before anyone looks.
Cost and Profitability Consulting · 150+ models since 2010 · TDABC
The whale curve in banking is steep: the top 20 percent of customers can represent 150 to 300 percent of profit, and 30 percent or more of relationships are unprofitable once cost to serve is loaded. A blended cost rate hides this. The sector patterns prove the size of the prize: a large retail bank cut several hundred million of cost and lifted market value by billions over eighteen months with TDABC; a global brokerage eliminated over half a billion of cost; a regional bank booked a seven-figure annual improvement in year one. The margin was always there, hidden inside a blended rate and a month-long close.
One average hides two opposite businesses.
A bank's customer base is really two businesses wearing one number: the relationships that generate far more profit than their share, and the ones that consume more cost than they return. A blended cost rate reports only the net, so the loss-making tail is cancelled out before it is ever seen. Until each customer carries their own cost to serve, the cross-subsidy is permanent and unmanaged, and the bank keeps pricing, targeting and rewarding relationships it cannot actually value.
CUSTOMERS, RANKED BY CUMULATIVE PROFIT
Illustrative. Cumulative profit climbs well past 100 percent on the best customers, then a long tail of unprofitable relationships drags it back once cost to serve is loaded. The gap is the cross-subsidy.
Hundreds of millions, hidden in plain sight.
The sector patterns are not marginal. As illustrative examples, a large retail bank used TDABC over a terabyte-scale data set processed overnight to cut several hundred million of cost and lift its market value by billions over eighteen months, while collapsing reporting from over a month to a few days. A global brokerage eliminated over half a billion of cost and saw its share price climb sharply after replacing a legacy system that took over a month to produce a single report. A regional bank booked a seven-figure annual improvement in year one. The common thread is not a clever trick; it is finally seeing profit per customer.
SAME REVENUE, A HUNDREDFOLD DIFFERENCE IN COST
Illustrative sector pattern. Identical sales, opposite cost structures. Profit per customer only appears once the cost to serve is loaded onto the relationship that caused it.
Reprice and redirect before you exit.
Load cost to serve
Run the channel and transaction time equations to net profit per customer, not a blended rate.
Rank by net
Build the whale curve. The unprofitable tail and the over-performing head both become explicit.
Reprice or steer
Adjust fees, minimums or channel behaviour for the tail, the levers that made the relationship expensive.
Protect the head
Know which 20 percent carry the bank, and defend those relationships deliberately, not by accident.
Frequently asked questions
- How many bank customers are unprofitable?
- Once cost to serve is fully loaded, 30 percent or more of banking relationships are typically unprofitable, while the top 20 percent of customers can represent 150 to 300 percent of profit. A blended cost rate hides this because the profitable customers subsidise the loss-making ones inside one average.
- What is the whale curve in banking?
- A chart of cumulative profit with customers ranked from most to least profitable. It rises well above 100 percent of total profit on the best customers, then falls as unprofitable relationships are added. The gap between the peak and 100 percent is the value the long tail destroys, value a blended rate nets away invisibly.
- What is the size of the prize in banking?
- The sector patterns are large. As illustrative examples, a large retail bank cut several hundred million of cost and lifted market value by billions over eighteen months using TDABC; a global brokerage eliminated over half a billion of cost; and a regional bank booked a seven-figure annual improvement in year one. The margin was always there, hidden inside a blended rate and a month-long close.
See which relationships actually fund the bank.
The Profit Check takes five minutes and no data upload. It points to where your unprofitable tail is most likely hiding, and what making it visible is worth.