A top lieutenant to billionaire Steven A. Cohen was convicted of insider trading Wednesday in a verdict that could strengthen the government's outstanding cases involving the storied hedge fund Cohen created two decades ago.

After two days of deliberation, a federal jury in Manhattan found Michael Steinberg guilty of trading on illegal tips involving technology stocks. While eight employees of SAC Capital Advisors have been accused or convicted of insider trading over the years, Steinberg was the highest-ranking among them and a longtime Cohen confidant.

His case was also the most challenging for the government, some legal experts said. Prosecutors needed to prove that Steinberg knew the information he traded on was illegally obtained, even though he was a few steps removed from the source of the tip.