MELBOURNE (Standard&Poor's) Aug. 20, 2013--Standard&Poor's Ratings Services said today that its ratings on National Australia Bank Ltd. (NAB; AA-/Stable/A-1+) are unchanged following an announcement by the bank today of its third-quarter trading update for the nine months to June 30, 2013. Major features of NAB's announcement are consistent with our ratings view. Quarterly performance for major operating divisions was broadly in line with rating expectations. Further, key measures of performance, including those associated with asset quality, capital, and earnings, cause us no immediate concern at the current rating level, although will be monitored for continuing ratings congruence. A pleasing, though not unexpected, aspect of the announcement was that there were no new or emerging concerns regarding