Meet the team
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Maria Los
Deputy Chairman, Head of Client Advisory Americas
BIOGRAPHY
Maria C. Los, Deputy Chairman & Head of Client Advisory Americas, works with many of Christie’s most important clients who buy and sell at auction as well as privately. Collaborating closely with her specialist colleagues, she ensures that these collectors are advised effectively. Maria’s longstanding international client relationships have also contributed to several significant cross-departmental consignments for the firm. Maria joined Christie’s in 1996 as an account manager assistant in the Estates, Appraisals & Valuations Department. She went on to spend ten years in Client Advisory followed by two years in the Jewelry Department. She was promoted to the Chairman’s Office in 2009, relaunched Client Advisory in 2011 and was named Deputy Chairman in 2014. Prior to joining Christie’s, she worked at the National Endowment for the Arts in Washington, D.C. in their Visual Artists Fellowships Program. Maria, who is Greek-American, received her B.S. in French and Italian and her M.A. in Liberal Studies from Georgetown University.
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Margot Rosenberg
Deputy Chairman
BIOGRAPHY
Margot Rosenberg, Deputy Chairman, joined Christie’s Client Advisory Department as Senior Relationship Director in 2011. Over more than 25 years in the auction business, both in specialist departments and Client Advisory, Margot advises a bespoke group of Christie’s top clients. She works collaboratively with individual sale heads and specialists across the business as a trusted advisor on buying and selling, both privately and at auction. She was the Christie’s lead in the landmark Paul G. Allen collection, the largest sale in auction history ($1.7 billion). She has been integral in selling masterpieces across all categories and in all our marquee auctions including The Collection of Elizabeth Taylor, The Peggy and David Rockefeller Collection, The Barney A. Ebsworth. Prior to joining the Chairman’s Office, Margot was the Department Head of American Decorative Arts and led that team in the most successful sales in the field. She appeared regularly on Antiques Roadshow. Margot holds a B.A. in Art History from Emory University.
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Sarah El-Tamer
Vice President, Client Relationship Director
BIOGRAPHY
Sarah El-Tamer joined the Client Advisory Department in 2023, bringing with her 13 years of experience working in Christie’s 20th and 21st Century Art Departments. As Vice President, Client Relationship Director, Sarah has broadened her work with collectors, using her specialist expertise to cultivate their cross-departmental interests for Christie’s globally. In her prior position within the Impressionist and Modern Art Department, Sarah served as the Head of Day Sales for nearly five years, spearheading some of the most successful sales ever in the category. Other highlights in her career thus far include her launch of the Picasso Ceramics Online Sales in 2014, leading six consecutive 100% sold-by-lot “white glove” sales, as well as serving as Head of Sale for Fine Art in the Ann & Gordon Getty Collection Sales in October 2022, which were also 100% sold. Additionally, Sarah is one of Christie’s newest auctioneers, having taken her first auction in May 2023. Sarah received a Bachelor of Arts degree from Columbia University in Art History and Economics. A native New Yorker with Lebanese heritage, Sarah is fluent in Arabic and French.
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Laura Betrian Waelbroeck
Vice President, Client Relationship Director
BIOGRAPHY
Laura Betrian Waelbroeck joined Christie’s Chairman’s Office in 2014. As Vice President, Client Relationship Director, Laura works to cultivate relationships with Christie’s new and existing clients, providing comprehensive support to collectors across diverse categories. She received her Bachelor of Arts from Columbia University in 2012 and her Master of Studies in the History of Art from Balliol College, Oxford in 2013, where she was a Mica and Ahmet Ertegun Scholar. She is fluent in French and Spanish.
Name:Laura Betrián Waelbroeck
Position:Vice President, Client Relationship Director
lwaelbroeck@christies.com -
Abigail Bisbee Dean
Vice President, Client Relationship Director
BIOGRAPHY
As Client Relationship Director, Abigail Bisbee Dean provides bespoke support to Christie’s clients who have varied collecting interests. Abigail began her career at Christie’s in 2014 as the American Art Sale Coordinator, managing the department’s biannual live and online auctions and providing support with private sale transactions. She is also a charity auctioneer. Abigail attended Georgetown University’s Edmund A. Walsh School of Foreign Service where she majored in Culture and Politics, receiving her Bachelor of Science in Foreign Service. Following her undergraduate career, she earned her Master in Art & Museum Studies, also from Georgetown University and received a certificate in Art and Business from Sotheby’s Institute of Art, London.
Name:Abigail Bisbee Dean
Position:Vice President, Client Relationship Director
abisbee@christies.com -
Sophie Jensen
Senior Client Relationship Coordinator
BIOGRAPHY
Sophie Jensen is a Senior Client Relationship Coordinator. In her role, she supports the logistical and administrative needs of the team’s Deputy Chairman, providing their important clients with bespoke service. Sophie joined Christie’s in 2021 as a Sale Coordinator in Old Master Paintings, where she facilitated the department’s biannual live and online auctions. Sophie earned her BA in Arts and Visual Culture at Bates College in 2019 and in 2021 went on to receive her Masters in Art, Law and Business at Christie’s Education in New York.
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