In an interview on CNBC’s Squawk Box, Goldman Sachs CEO David Solomon advised investors not to expect the bull run in stocks and other assets to continue at their current levels. With equities enjoying 3 straight years of returns in the double digits (according to the S&P 500 measurements), driven with help from the Fed, the boom has poured into other assets such as real estate, cryptocurrency, and art. But Solomon predicts that those returns aren’t going to continue in perpetuity.

Despite a 48% surge this year, Solomon also told CNBC that he believes Goldman’s shares were relatively undervalued and underappreciated, with the industry under the mistake perception that bank earnings are more volatile than they actually are. “…the earnings power of the traditional financial services sector is quite powerful,” he said, “and we get a very, very low multiple on those earnings.”

And while Solomon said he personally doesn’t own cryptocurrency, clients should be allowed to speculate on it if they wish. More important than crypto, he said, is the shift toward digital channels for financial services, and Goldman recently announced an Amazon-backed cloud offering for Wall Street firms. “I’m a big believer in the…disruption that is occurring…” Solomon said, calling it “a massive shift.”