Tony Thomas, associate director of equity strategies for Morningstar Research Services LLC, a subsidiary of Morningstar Inc., Chicago, said in a phone interview that the story for the past year was pretty simple. "Much of what we've seen from these top performers has to do with AI generally and NVIDIA (Corp.) in particular," Mr. Thomas said, "and that powered a good number of these strategies in the second quarter, and that gave them a great 12-month results as well." For the year ended June 30, NVIDIA gained 179.3%.