New research from SearchIgnite and RBC Capital Markets found that  since the launch of Yahoo's ad system Panama more than a month ago,  big brand marketers have benefited most from the Quality Index. The  feature is a score for ads that estimates average position and click  forecasts based on budget allocation and ad quality. In addition, Yahoo's click-through rate has gone up and its cost-per- click has been stable. The research also found that Yahoo's market  share for paid search advertising stabilized after dropping suddenly  in 2006. The biggest key finding is that Panama has been overall very good  for large brand marketers thus far - but keep in mind that it's  really still too early to tell, said Roger Barnette, president of  SearchIgnite, Atlanta, GA. The report tracked more than 7.5 billion impressions and 85 million  clicks across more than 500 marketers. It was based on research