Yeah, what a spike! It's moderated to only 18-19% now, but still, remarkable. The announcement of NBKC community bank joining Upstart doesn't seem at all significant enough to cause such exuberance. I think it's just one factor of several, and the NBKC addition just a minor factor.

The biggest factor is probably just exuberant buying of tech stocks in general today. UPST isn't the only one: META is up ~22%, Google 7%, etc ...

Upstart is probably more specifically benefiting from fears of inflation and recession dropping with recent reports and Fed actions. When interest rates level out and then start dropping, Upstart's prospects vastly improve, and it seems we're nearing peak short term interest rates if we haven't already hit them.

I suppose the market is also rewarding Upstart's moves to reduce expenses significantly by cutting staff. It shows they care about reducing cash burn and aren't pursuing a crazy growth at any cost strategy that might end up in bankruptcy.

To illustrate that the bank signing is a minor factor, just compare market action a couple months ago when Upstart announced that Carver Federal Savings Bank was a now a partner. UPST was down that day, and continued down for a month. Carver absolutely dwarfs NBKC in size, though, with assets of $1.7 trillion, compared to NBKC assets of a little over $1 billion.