Brandon John Williams
May 4, 2026
Dissertation Chapters:
with Richard Van Weelden and Alistair Wilson
with Lester Lusher and Lise Vesterlund
There is not one banking sector. There are two—one for the poor and for the rest of us—just as there are two housing markets and two labor markets.
- Matthew Desmond, Poverty by America
Do consumer moral concerns/repugnance maintain segmented markets and exclude some consumers from the standard market?
Commercial banks could offer payday loans with fees up to eight times less than the standard market price and still turn a profit.... But getting into the payday loan business would mean offering financial products designed specifically for a down-market clientele, loans that would come with APRs between 40 and 80 percent and serious reputational baggage. So far the suits at JPMorgan Chase and Citigroup have decided it is not worth it.
-Matthew Desmond, Poverty by America
Data from Pew unless otherwise noted
Data from Pew unless otherwise noted
Center for Responsible Lending
Alabama, Idaho, South Carolina, Utah and Wisconsin have no cap except for "unconscionable" loans
Interest rates in the payday sector considerably exceed typical maximum credit card APR (26%) or personal loan APR (21%)
What could explain the segmented market structure?
A model of traditional loans vs payday lending captures:
Consumers have types defined by their market access
with outside options
High-type consumers care about the brand reputation of a firm. For consumer k looking at firm i:
is a exploitation-aversion (repugnance tolerance or moral disutility) parameter that penalizes exploitation by the firm with heterogeneity at the individual level drawn from
and share
is an increasing and weakly convex function (some exploitation might be okay)
Firms are indexed
Each firm observes a private signal about the transaction value:
The high market has many well-informed competitors while the low market has fewer firms and signals are weaker
Firms observe the signal and submit a bid (rationally anticipating a winner's curse):
which accounts for winner's curse discount, which is increasing in the weakness of the signal and decreasing in the number of firms:
The winner's curse discount:
gives a nice measure of perceived exploitation without assuming predatory behavior on behalf of the firms in the low market:
More firms reduces perceived exploitation while less informative signals increase it.
Note: I believe the model can accommodate additional perceived exploitation not owing solely to a winner's curse markup, but I have not proven this yet and it is possible it would require additional assumptions.
The winner's curse discount:
also allows for some positive profit to banks in the primary market.
The firms in the high market then face a trade-off:
Note: I start under the assumption of a segmented market. I have not yet shown if my model primatives can accommodate starting there.
The firm choice becomes to stay clean:
And lose some share of consumers who would find their entry into the low market to be repugnant, determined by
Or to enter into the low market and extract a share of the premium using the better assessment technology:
Model predictions:
Things currently not addressed:
An ideal experiment would answer:
Possible designs:
I am looking forward to working hard with your guidance!