Many on Wall Street like to style themselves as contrarians, but few are swimming against the current as hard as Jay Goldberg, the lone bear on high-flying Nvidia Corp.

Sitting in the cluttered home office on the ground floor of his three-story Victorian near San Francisco’s Haight-Ashbury neighborhood, the good-humored bespectacled 54-year-old senior analyst at Seaport Global Securities hardly looks or sounds like a stock-market iconoclast. With his collection of ancient technological devices, including a brick-shaped cell phone from the 1980s that looks like it could’ve been used by Gordon Gekko in the movie Wall Street, the married father of three comes across as a low-key gadget geek.