Less than three years into its pivot to retail banking for the masses, Goldman Sachs CEO David Solomon still feels like an underdog.

The firm's Marcus business gathers $1 billion in deposits a month and recently announced its first credit card with Apple, but that progress has yet to be reflected in Goldman's stock, which trades at a discount compared with rivals. So when J.D. Power presented the firm with an award this week for customer satisfaction in personal loans, topping other big banks and fintech upstarts, Solomon soaked in the moment.

"We started out to try to create a business that would disrupt what's a big broad industry by really focusing on our customers, on our clients in a way that we would provide better service, better solutions, deal with pain points," Solomon told about 200 Marcus workers who gathered on the 26th floor of the firm's New York headquarters for a meeting attended by CNBC.

"Now, we're getting absolutely no credit from anybody else in the investing community about that yet," Solomon said.

"If we were out in Silicon Valley and made 20% of the progress that we've made, we would get a lot of credit and people would be throwing money at us to own a piece of this business," he added. "But nestled inside little old Goldman Sachs, we're just going to have to prove it over time."

In the post-financial crisis era, retail banking fueled by cheap deposits earns a far higher return than capital markets businesses, which is why Goldman is making this push. But Marcus sits within a company that still gets most of its revenue from Wall Street activities like trading and mergers advice, and the trading businesses in particular have been exposed to an industrywide decline. Goldman shares have fallen 19% in the past year.

Despite the investor indifference, Goldman's Marcus business is at an inflection point. Begun in late 2016, it has essentially two products: high-interest savings and personal loans. The bank has gathered about $48 billion in deposits and made $5 billion in loans so far, but new offerings are coming.

Next up is the Apple Card, and after that, a digital wealth management service for the mass affluent, executives have said. At some point, the personal finance app Goldman bought last year, Clarity Money, will join the Marcus brand. Ultimately, the bank could offer the full spectrum of retail finance products, either directly or through partnerships, from checking accounts to mortgages and insurance.

Goldman doesn't yet disclose much about Marcus, which is part of its investing and lending division, including how much revenue it generates.