Investors flocked to safe-haven assets such as Treasurys and gold on Monday amid an extraordinary plan to backstop the banking system and limit the impact from the collapse of Silicon Valley Bank.

The benchmark 10-year Treasury yield fell nearly 20 basis points to 3.50%, touching the lowest level since Feb.3. The 10-year rate last traded around 3.54%. The yield on the 2-year Treasury tumbled more than 40 basis points to 4.16%, also the lowest in over five weeks. Yields move inversely to prices and one basis point equals 0.01%. The iShares 20+ Treasury Bond ETF jumped 1.6%.

Meanwhile, spot gold was up 0.9% at $1,884.87 per ounce. Earlier in the session, prices hit their highest since early Feb at $1,893.96. U.S. gold futures gained 1.2% to $1,889.40. Investors tend to rotate into the metal during financial shocks. What's more, lower interest rates decrease the opportunity cost of holding zero-yielding gold.

Investors sought safety as banking regulators rushed to backstop depositors with money at Silicon Valley Bank and now-shattered Signature Bank, seeking to ease systemic contagion fears. Depositors at both failed institutions will have full access to their deposits as part of multiple moves that officials approved over the weekend.

"Angst about what might be 'the next shoe to fall' spread through the markets like wildfire," said John Stoltzfus, chief investment strategist at Oppenheimer Asset Management. "We continue to believe that while we are not yet out of the woods."

Stock futures initially opened higher Sunday evening on the government's plans, but have since rolled over.

Concerns about the health of smaller, regional banks deepened after regulators shut down a second institution Sunday. First Republic Bank led a decline in bank shares Monday after it said Sunday it had received additional liquidity from the Federal Reserve and JPMorgan Chase.

San Francisco's First Republic shares lost 70% in premarket trading Monday after declining 33% last week. PacWest Bancorp dropped 37%, and Western Alliance Bancorp lost 29% in the premarket. Zions Bancorporation shed 11%, while KeyCorp fell 10%.

SVB's collapse marked the largest U.S. banking failure since the 2008 financial crisis — and the second-largest ever.  HSBC on Monday announced a deal to buy the U.K. subsidiary of the failed U.S. tech startup lender following all-night talks.