The Bank of Japan's decision to explicitly control sovereign bond yields will probably cap interest rates, bolstering demand for corporate debt offering extra premiums, according to analysts.

The BOJ added what it calls “ yield curve control” to its stimulus mix on Wednesday and said it will seek to keep the yield on the 10-year government bond “around zero.” The average yield on Japanese corporate bonds ended that day at 0.24%, according to Nomura BPI indexes, compared with minus 0.035% for the nation's 10-year debt.

“Investors are going to have to continue to invest in credit products such as corporate bonds to get spreads because looking over a long period we aren't likely to see a big jump in interest rates,” said Hidetoshi Ohashi, the chief credit strategist in Tokyo at Mizuho Securities Co., a unit of Japan's third-largest lender. While the BOJ has tweaked its policies, inflation expectations aren't likely to rise because of it, and market borrowing rates will probably stay low for a very long time, he said.