Theflyonthewall.com was judged to have misappropriated the information by its quick publication of data, which the banks claimed subsequently impacted business.
Publication of data before markets open will now be delayed until after 10:00 while information on daytime trades will have a two-hour embargo.
Judge Denise Cote told the Wall Street Journal: â[It] bears noting that it does not matter to the firms whether the unauthorized distribution is through a small internet company like Fly or through media giants like Bloomberg, Thomson Reuters or Dow Jones.
âThe damage is caused not by the identity of the publisher, but by the timely and systematic unauthorized redistribution of the firms' recommendations, whatever the medium.â
Glenn Ostrager, a lawyer representing the website, said that it would appeal against the ruling.
He claimed that the decision was "at variance with existing lawâ.
The injunction was brought by the three banks in March.
By Jim Ottewill