The hedge fund SAC Capital Advisors is moving closer to a plea deal with prosecutors that would force it to wind down its business of managing money for outside investors, punctuating its decline from the envy of Wall Street to a firm caught in the government’s cross hairs, the New York Times DealBook blog reported yesterday. An agreement to stop operating as an investment adviser is one feature of a larger agreement SAC is negotiating as it seeks to resolve insider trading charges. The plea deal would also require SAC to plead guilty to criminal misconduct and pay more than $1 billion in penalties, a record for an insider trading prosecution.