WASHINGTON — A fourth market participant, Mark Zaino, has pleaded guilty to participating in bid-rigging and fraud conspiracies in connection with municipal investment contracts and derivatives, the Justice Department announced yesterday.

Zaino, who formerly worked on the muni derivatives and guaranteed investment contract desk at UBS AG, engaged in the bid-rigging conspiracy from as early as October 2001 until March 2006, Justice lawyers said.

Subscribe Now

Independent and authoritative analysis and perspective for the bond buying industry.

14-Day Free Trial

No credit card required. Complete access to articles, breaking news and industry data.