Goldman Sachs research analyst Marc Irizarry's published rating on mutual-fund manager Janus Capital was a lacklustre "neutral" in early April 2008. But at an internal meeting that month, the analyst told dozens of Goldman's traders the stock was likely to head higher, company documents show.

The next day, research-department employees at Goldman called about 50 favoured clients of the big securities firm with the same tip, including hedge-fund companies Citadel Investment Group and SAC Capital Advisors, the documents indicate. Readers of Irizarry's research didn't find out he was bullish until his written report was issued six days later, after Janus shares had jumped 5.8%.