Shares of Upstart Holdings (UPST 2.76%) charged sharply on Wednesday, climbing as much as 20.9%. When the market closed, the stock was still up 20.3%.

The major market indexes were trading higher after the Federal Reserve Bank decided to hold interest rates steady in its last rate decision of 2023 and signaled potential rate cuts next year. While that was likely the primary catalyst that pushed the fintech stock higher, the company also announced a new banking partner.

A new financial partner

In a press release that dropped early Wednesday, the company announced that Mutual Security Credit Union had selected Upstart's artificial intelligence (AI)-based lending system "to provide personal loans to more people."

The financial institution, which operates in western Connecticut and has assets of more than $390 million, has been an Upstart Referral Network lending partner since September. The credit union says Upstart "allows us to extend our reach and provide a modern, digital-first experience to drive more inclusive lending within the community."

This is a significant vote of confidence for Upstart's AI-powered system, which assesses more than 1,500 variables to determine creditworthiness, resulting in more loans to consumers at lower annual percentage rates (APRs). This latest win also adds to the roster of more than 100 banks and credit unions in Upstart's network.

It's (also) the economy

One of the biggest factors that weighed on Upstart over the past couple of years is the quickly rising interest rate environment. As rates increase, the spread between what a bank pays depositors and what it earns from loans shrinks, eating into profit margins. Furthermore, the one-two punch of high inflation and rising rates pressured consumers, raising the risk of loan defaults.

The decision by the Fed to hold interest rates steady in anticipation of rate cuts next year is good news for banks, and by default, good news for Upstart. Add to that the company's growing list of banking partners, and it was a pretty good day for Upstart and its investors.