Iberdrola's credit ratings are set to climb while Endesa, the Spanish electricity company it hopes to merge with, is heading in the other direction, in a classic case of consolidation convergence.

Moody's Investors Service today (Thursday) put Iberdrola's A1 rating under review for a possible upgrade and maintained Endesa's Aa3 rating under review for a possible downgrade following approval of the merger by the boards of directors.