The world's leading mutual fund company, Fidelity Investments, reduced its stake in PetroChina by 91% in the first quarter, following pressure by human rights groups over the Chinese oil firm's activities in Sudan. A regulatory filing on Tuesday showed that Fidelity had reduced its holding of PetroChina American Depository Receipts to 420,916 as of March 31 from about 4.5 million at the end of December, Reuters reported. Fidelity declined to comment on the reason for its action but it comes after strong petitioning from groups such as the Save Darfur Coalition, the Sudan Divestment Task Force and Fidelity out of Sudan. Their principal targets have been Fidelity and Warren Buffett's investment firm Berkshire Hathaway, another big PetroChina shareholder. John Bonnanzio, editor of independent newsletter Fidelity Insight, said Fidelity appeared to have "buckled to the mounting political pressure". PetroChina is said to be the leading Chinese investor in Sudan, effectively generating funds for a government that is allegedly perpetrating genocide in the country's Darfur region.