A secret source of trading ideas for some of the world’s biggest hedge funds operates one door down from a dentist’s office in midtown Manhattan.

Working from a 300-square-foot trading room adorned with a flat screen TV and four wall clocks, Ari Bergmann has acted as an under-the-radar consultant to Steven Cohen's SAC Capital Advisors, Daniel Loeb's Third Point and Richard Perry's Perry Capital, according to people familiar with the matter.