@ctuser1 - Bofa, WF, and Chase are the dominate consumer banks. They have the most customers to spread costs over and generate low cost deposits. I won't speak to Citi, but they have a good retail franchise as well. They're affectionately known as the Big 4.
I'm going to speak directly related to the institution I worked at, but going through ABA's banking school and having friends working elsewhere, I can say with some confidence this reporting is similar from bank to bank.
The "segment profitability" numbers they report has subjectivity. Here are a few issues I've picked up on.
Transfer pricing: The consumer segment profitability is primarily driven by consumer transaction deposits and fees. The bank assigns an internal number to those deposits called "transfer pricing" and gives the P&L of the consumer bank credit for providing those deposits over to the commercial/corporate bank. The commercial/corporate bank is primarily making the loans while the consumer bank provides a chunk of the funding. The *only* bank I can think of that's different is Capital One, just because their commercial business dwarfs their consumer business and their executives think they are running a fintech company. Transfer pricing is the first form of subjectivity, they are picking a number and crediting the consumer bank for loaning the funds over to be loaned out by the commercial bank.
So then you have your branches - They service both consumer and small business deposits. Some banks lump small business into their retail bank while others don't. A smaller business client is wildly profitable for a bank. They tend to carry the highest transaction deposits relative to costs and even when you loan them money, they have the highest deposit balances relative to loans. The bank I worked for allocated all of the branch cost to retail, which was insane.
All that being said, I've watched Bank of America stick to their model for the entire fifteen years I was in the industry. 1) Be the dominate consumer bank generating the lowest cost of funds 2) Loan those low cost funds out to the largest businesses in the country.
Whether we say they make their segment money through the low cost advantage on deposits or through the interest income earned on loans that they can do at a lower cost than others, they win either way. I always admired a client of mine who thought the same thing in 2009 and put $500,000 in their stock.