Anyone could be a corporate bond trader in 2012. Almost everything rose in value.

Investment-grade corporate bonds returned 9.6% in the US and 13.3% in Europe through December 24, Barclays indexes show; high-yield bonds, excluding financial companies, returned 15.0% and 23.8%, respectively. But with yields now extremely low-the average global investment-grade bond yields just 2.6%-investors will have to work much harder for gains in 2013.