Blocks from Fidelity’s headquarters, a team of quants toil in relative anonymity. They’re also a key weapon in the investment firm’s fight to take on all rivals, from Vanguard Group to Robinhood Markets.

Geode Capital Management was spun out of the Boston-based firm nearly two decades ago. At the time, Fidelity Investments was content to be undercut by rivals in the low-cost index business and didn’t want to overshadow its powerful and famous stock pickers.