Antiquorum, the world’s leading auction house for timepieces, has sold 50 percent of its equity to ArtistHouse Holdings Inc., a Japanese company, for $30 million. The deal enables Antiquorum to expand its Asian, publishing, and Internet operations.

The deal, effective Jan. 23, makes ArtistHouse an equal partner with Osvaldo Patrizzi, Antiquorum’s founder, chairman, and chief executive officer. Under terms of the pact, he remains chairman and chief executive officer.

ArtistHouse has a variety of businesses in entertainment, publishing, and Internet technology. It will aid Antiquorum’s expansion in the Asian market, said Antiquorum, which has offices in Hong Kong, Shanghai, and Tokyo, and held its first Hong Kong auction in 1978. ArtistHouse will initially focus on expanding Antiquorum Japan’s operations.

ArtistHouse also intends to significantly increase Antiquorum’s publishing business, launch an Antiquorum customer-to- customer Web site (www.C2Ctime.com), and provide what Antiquorum calls substantial financial support.

Antiquorum, founded in 1971, is based in Geneva, with branches in 10 cities serving 13 countries, including London, Moscow, New York, and Paris. About 80 percent of all watches sold at auction above $800,000 in recent years were sold by Antiquorum.

ArtistHouse Group, founded in 2000, is located in Tokyo. It consists of a holding company and eight subsidiaries dealing in book publishing; film, DVD, CD and digital music distribution; finance and investment; music instrument retailing; and e-commerce.