Nasdaq’s deal to buy Philadelphia Stock Exchange (PHLX) for $652m may still hit some snags as one prominent investor is considering a counter bid for the exchange and PHLX shareholders are battling over distributions from a recent settlement.

Thomas Caldwell, chairman of Caldwell Financial in Toronto, told FO Week that he was considering making a bid for PHLX, but has started to reconsider his decision.

“It’s a case of being...