All exchanges provulgate volume and open interest daily without charge. Data vendors also send this information to subscribers. I subscribe to DJ, but anyone could get the data without charge at exchange sites.
All exchanges provulgate volume and open interest daily without charge. Data vendors also send this information to subscribers. I subscribe to DJ, but anyone could get the data without charge at exchange sites.
I assumed the puts in question were exchange-traded; since bank dealers who divulge clients' positions get fired. If a large client puts on a monster trade with a bank's dealer, bank management could easily find the dealer.
If a whale does an egregiously large trade with, say, Citibank; Citibank's risk managers will know it. The risk managers will also know the name of the dealer who did the trade; the managers will then fire the dealer for leaking highly sensitive proprietary information.
If a whale, say, Citadel, finds out Citibank is leaking its trades to some pay-per-view forex rag; I'd guess Ken Griffin would personally rip off someone's head on Citi's trading floor.