S&P Global Ratings on May 21 upgraded the long-term issuer credit rating of Credit Suisse Group AG unit Credit Suisse AG to A+ from A.

The agency also upgraded the long- and short-term resolution counterparty ratings to AA-/A-1+ from A+/A-1 of the group and its other units in Switzerland, the U.K., Spain and Germany. The outlook on the long-term issuer credit ratings was revised to stable from positive.

It affirmed the short-term issuer credit ratings at A-1 for all the subsidiaries. It also raised the long-term resolution counterparty rating of the bank's U.S. unit Credit Suisse Securities (USA) LLC to A+ from A, while affirming the short-term resolution counterparty rating at A-1.

S&P Global Ratings affirmed the long-term issuer credit rating at BBB+ for Credit Suisse Group, with a stable outlook.

The outlook on the long-term ratings of all the units is stable.

The ratings upgrade comes from sustained earnings improvement by Credit Suisse following the completion of a three-year restructuring program, the agency said. The stable outlook in all the units reflects the bank's franchise in global wealth management and domestic corporate retail banking will continue to support group earnings.