Bond investors tend to fixate on worst-case scenarios, and that has been the case in the past two weeks. Bonds rallied and yields tumbled around the world, with holders of 30-year US Treasury bonds earning a supersize (for bonds) 8.4% on their money over 10 trading sessions.

Run-of-the-mill worries about corporate profits or tighter monetary policy can’t be blamed for the latest gyrations, which sent 10-year Treasury yields as low as 1.6% Wednesday, especially as three Asian central banks announced surprise rate cuts this past week.