William Felix Browder is an American-born British financier and political activist. He is the CEO and co-founder of Hermitage Capital Management, the investment advisor to the Hermitage Fund, which at a time was the largest foreign portfolio investor in Russia. The Hermitage Fund was founded in partnership with Republic National Bank, with $25 million in seed capital. The fund, and associated accounts, eventually grew to $4.5 billion of assets under management. In 1997, the Hermitage Fund was the best-performing fund in the world, up by 238%. Browder's primary investment strategy was shareholder rights activism. Browder took on large Russian companies such as Gazprom, Surgutneftegaz, Unified Energy Systems, and Sidanco. In retaliation, on 13 November 2005, Browder was refused entry to Russia, deported to the UK, and declared a threat to Russian national security.