The $2.4 billion Alger Spectra Fund is a skilled marathoner. Its performance ranks in the top 24%, 6% and 1% of its large-cap growth rivals tracked by Morningstar Inc. over three, five and 10 years. Patrick Kelly, 37 years old, has run the fund since Sept. 24, 2004. He looks for growth companies that are undergoing positive dynamic change. Kelly discussed his approach with IBD from his office in Manhattan. IBD: You look for two types of good