Not too many top-ranked analysts would change sectors to try something new, but that is exactly what B. Alexander Henderson did. At Prudential-Bache Securities, which he joined in 1986, Henderson was ranked No. 1 in Photography & Electronic Imaging ten times, but he says it wasnt much fun during the tech stock run-up of the late 1990s. In December 1999 he went to the firms director of research and told him he wanted to cover data networking instead. Henderson got the post but was required to cover both industries. In 2000 he moved to Citigroup/Salomon Smith Barney; within three years he was No. 1 in Data Networking. But by then the technology bubble had burst, and he says it took some time to repair the credibility loss with clients. Its about being clear and up front, never overselling your knowledge base, says Henderson, who left Citi in 2007 and now works as a tech analyst for Miller Tabak & Co. Its critical that people understand what is fact, what is theory and what the premises are of your research.