State Street Bank and Trust Co., Boston, entered a 50/50 joint venture with Mansion House Group Ltd. of Hong Kong to provide asset management and mutual fund services in Hong Kong, China and the region.Nicholas A. Lopardo, chairm an and chief executive officer of State Street Global Advisors, will be chairman of the venture, named State Street Mansion House Investment Management Services Ltd.SSgA has full investment operations in Hong Kong. Worldwide, SSgA manages $300 billion in assets, but aspires to have $500 billion in assets under management by 2000, of which a third is expected to come from non-U.S. sources.Evans C. Lowe, now chairman and chief executive officer of Mansion Hous e Group, will be vice chairman of the new firm.Mansion House is active in stock brokerage, asset management and direct investment in China. Mansion House's role in the venture is to provide investment and administrative services.Bo th companies see enormous opportunity in Hong Kong and China in the next decade. Messrs. Lopardo and Lowe met with senior Chinese government officials earlier this year, as well as Hong Kong's chief executive-designate, C.H. Tung, to express their confidence in the region's positive investment climate.