UBS cuts Alumina (AWC.AU) to Reduce from Neutral after completes buyback at 14% discount to weighted average price over 5 days to April 20. Broker says buyback adds 1% to EPS. But share price has been supported of late by this and stock now trading at 7% premium to broker's valuation and at 14x broker's 2007 EPS estimate, against Alcoa (AAI.AU) and Alcan on 10x and 9x respectively. Has A$7.15 price target vs stock early down 1.3% at A$7.11.