The Bill and Melinda Gates Foundation has purchased shares in nine big pharmaceutical companies valued at nearly $205 million -- an investment likely to attract attention more for its symbolism than its size.

The foundation, the nation's largest with an endowment of $24.2 billion from Microsoft Corp. Chairman Bill Gates and his wife, already is a major force in international health issues, contributing $555 million in 2000 alone to global health programs. The organization has emerged as a prominent voice in the debate over...