Does Goldman Profit from Its Clients' Losses?

The New York Times reports that a Goldman Sachs Group (GS) email to clients reveals that the firm places trades before recommending them to clients, and sometimes even bets against clients' positions -- presumably when it thinks those positions are money losers. The Times quotes an email to clients from Thomas C. Mazarakis, the head of Goldman's fundamental strategies group: "We may trade, and may have existing positions, based on trading ideas before we have discussed those trading ideas with you."