0454 GMT - National Australia Bank's recent share price rally and current trading multiples look hard to justify for its bears at Morgan Stanley. With an unchanged underweight rating on the stock, MS analysts point to the uncertain operating environment and the lender's weak earnings outlook. They believe that NAB's revenue growth is slowing and that it has limited flexibility on costs or capital. They suggest caution regarding NAB's credit quality in the current challenging macroeconomic environment, saying that it appears to be turning lower. MS has an unchanged target price of 34.00 Australian dollars on the stock. Shares are down 0.6% at A$39.21.