Female employees at startups typically get less than half the amount of equity of their male peers, according to a new study, highlighting one factor that has limited women’s involvement in the Silicon Valley wealth-generating machine.

Female employees own 47 cents for every dollar of equity a male employee owns, according to a new study released by Carta, a Palo Alto, Calif.-based company that helps startups manage employee and investor equity. The equity discrepancy is even more stark for female founders: Women founders...