Diana Adams will replace David Wallis as head of Ambac Assurance Corporation. Wallis has resigned as president and ceo and as a director of Ambac Assurance, effective 6 July. He will remain a director of Ambac Financial.

Wallis joined Ambac in 1996 first in its London office, where he was involved with developing and leading the European businesses, before moving to Ambac's New York headquarters in 2003 where he was a member of the risk management team. He was appointed president and ceo of Ambac in October 2008.

Adams, currently senior md, will become president and ceo on 7 July. She has also been appointed as a director of both Ambac Financial and Ambac Assurance, effective as of 7 July.

Adams is Ambac's chief administrative officer with executive responsibility for human resources, technology and administration. She is a member of the subsidiary Ambac Assurance UK Ltd, which she chaired between 2008 and 2010. Previously she oversaw Ambac's origination efforts in emerging markets and structured issuance, as well as international and structured finance.

Kevin Doyle will also step down as senior vp and general counsel on 29 July, to be replaced by Stephen Ksenak on 30 July.