Sotheby's announced on Monday that it would buy a boutique art advisory firm called Art Agency, Partners for a total up to $85 million. The deal is for $50 million with an additional $35 million pledged for undisclosed performance targets.

New York-based Art Agency, Partners is led by former New Museum curator Allan Schwartzman, former Christie’s postwar and contemporary art chairwoman Amy Cappellazzo, and investment banker Adam Chinn. The agency's staff of 15 will head to Sotheby's along with their client list. 

Schwartzman and Cappellazzo will join Marc Porter, also ex-Christie's, to lead the newly formed Fine Art Division, a strategic move by Sotheby's to expand globally in private sales and handle client services as advisors to top collectors, mostly in 20th-to-21st century art.