Commercial Bank has a AA+ (lka) rating from Fitch with a stable outlook, which was not changed.
Fitch upgraded the outlook of NDB's rating to positive in January after an announcement of merger talks was made.
Fitch said the 'positive' tag reflected the "benefits its creditors stood to gain by the bank being merged with a larger and higher rated entity."
The outlook on Commercial Bank was not changed as the proposed merger was not thought to have a significant impact on its credit profits.
"Since the merger has now been called off, NDB's rating outlook has been revised to Stable from Positive, while CB's ratings are affirmed," Fitch said.
Fitch has also given Commercial Bank an individual rating of 'D'