“The weakest links are cracking—and this this will not be the last one,” Beat Wittman, chairman of Switzerland’s Porta Advisors said Thursday on CNBC “Squawk Box Europe.”

Wittman was discussing the abrupt loss of confidence in Credit Suisse and its stock’s decline, as banking system contagion fears spread from the United States to Europe.

Meanwhile, U.S. Senate Banking Committee Chairman Sherrod Brown said Thursday that banks he has been talking with have reported "no fear" among customers after the failures of Silicon Valley Bank and Signature Bank.

Big banks like JPMorgan Chase & Co. and Bank of America are actually seeing an influx of customer deposits from smaller banks, Brown testified.

After Switzerland’s central bank said it would supply up to $54 billion to support Credit Suisse, shares of the beleaguered bank’s stock surged 20% Thursday.

“We have to step back and look, of course, at the viability of the business model [and] at the overall regulatory landscape,” Wittman said.

“I think the leadership of the bank has to really use, now, this lifetime to review their plan because, obviously, the capital markets have not bought the plan as we have seen by the performance of the equity price and the credit default swaps very recently.”

A jump in the cost for Wall Street banks to insure bonds against default, or CDS, have become another worrisome indicator of credit stress for investors amid the crisis at Credit Suisse and at U.S. regional banks.

According to S&P Global Market Intelligence, spreads on five-year CDS on JPMorgan Chase & Co., Bank of America Corp., Morgan Stanley and Wells Fargo shot up to their highest since October, while those for Goldman Sachs and Citigroup Inc. are highest since November.

‘SYSTEMIC RISK’

"Credit spreads are telling you there is systemic risk in the system," said Lance Roberts, chief investment strategist at RIA Advisors.

Wittman added: “The weakest links are cracking, and that’s just happening. That was entirely predictable—and this will not be the last one. So, now it is really time for policymakers to restore confidence and liquidity in the system—be it in the U.S., be it in Switzerland, or be it somewhere else.”

Asked how he would advise investors amidst the market volatility, Wittman said, “The upside momentum in inflation and interest rates is receding very clearly, so I think there is a very healthy underpinning in capital markets.”

Investors should stick with “high quality companies—that means strong management, strong balance sheets, strong value proposition,” Wittman continued. “And now you can pick them up at more attractive valuations.”

Dan Scott, head of multi-asset management at Vontobel and who used to work at Credit Suisse, said on CNBC’s “Squawk Box Europe” Thursday that the Zurich-based bank might even be worth consideration for some investors.

“Credit Suisse is still one of the world’s largest asset managers,” Scott said. “It has half a trillion in assets, and, certainly, this could be a great turnaround story if the execution is good.”

PRIVATE MARKETS' CREDIT EXPOSURE

Investors currently holding Credit Suisse might want “absolutely” want to remain patient, Scott said. “But, again, the stress that we’re seeing at the moment really should have been predictable.”

“When rates come up so fast, certain business models get challenges, and I don’t think it is a wealth management business model that gets challenged,” Scott added. “I think much more, and why we saw it at Silicon Valley Bank, is private markets are doing to get challenged.”