Morgan Stanley has hired Erik Siegel, formerly of UBS, as a collateralized debt obligation trader. Reached at his desk at Morgan Stanley in New York, Siegel declined to comment. He made the switch in recent weeks. Tony Tufariello, head of securitized products at Morgan Stanley, did not return a call seeking explanation on the hire. Secondary market activity in CDOs has increased markedly in recent months, but it could not be learned whether Siegel's hire is simply a reaction to this, or part of a broader expansion. At UBS, Siegel had traded structured credit products. Jeff Herlyn, co-head of CDO banking and trading in Stamford, Conn., did not return a call.