SYDNEY (S&P Global Ratings) Feb. 7, 2019--S&P Global Ratings said today that National Australia Bank Ltd.'s (AA-/Negative/A-1+) credit quality should remain unchanged following the departure of the bank's CEO and Board Chairman because we consider that the board and executive management have sufficient depth and breadth to fill the gap. We also believe that the group's strategic direction will remain broadly unchanged. Although these departures cast a shadow on the bank's culture and reputation in the short term, we don't expect it to cause any significant or lasting damage to the bank's franchise, expertise, or financial profile. In addition, we believe that NAB is strengthening its culture and governance, in line with the broader Australian banking industry following the issues