U.S. bond yields are spiking, raising fears of financial instability.

The 10-year Treasury yield has crossed 4.20% for the first time in months, while a stronger dollar pressures markets. Concerns over U.S. deficits are intensifying, leading to declines in Asian stocks for five of the last six sessions. Wall Street is feeling the heat too, with the Nikkei hitting a three-week low as investors grow increasingly cautious globally.