Jeff Wecker, president and CEO of Lime Brokerage, attributes the growth to high-frequency traders leaving their existing positions with sell-side proprietary trading desks and multi-strategy trading firms and seeking green opportunities. "Clearly, there has been a migration taking place in high-frequency trading," he says. "We have seen a growing number of sole proprietorships and we have seen people leaving existing high-frequency trading firms and going out on their own as well." These new