DUBAI (Reuters) - Returns for Kuwait’s sovereign fund, the Future Generations Fund, grew 33% in the year to March 31, the finance ministry said on Twitter. The fund is managed by the Kuwait Investment Authority (KIA), which had more than $580 billion in foreign assets at the end of last year, according to ratings agency Fitch. A government source said the bull run in U.S. stocks was one of the main drivers of the rise in the FGF’s returns, which increased by more than $150 billion in the last fiscal year. “We are overweight in the United States and we are overweight in U.S. stocks - more than 50% of our assets were stocks. This was very good for us,” the source said. “At the beginning of the fiscal year the markets were down significantly, and we started at a low base. We had cash and it was used to buy assets in markets that were up 50% in the last fiscal year.” Kuwait’s fiscal year runs from April 1 to March 31. Reporting by Ahmed Hagagy, Davide Barbuscia, Yousef Saba; Editing by David Goodman Our Standards: The Thomson Reuters Trust Principles.