This first appeared in This Week (September 30, 1951), and was reprinted in Queen’s Bureau of Investigation as “Swindle Department: Double Your Money.”
So, there is a Wall Street financier (known as “The Wizard of Amsterdam Avenue) who doubles the money given to him by janitors, shoe shine boys and school kids. Ellery alerts the police about this obvious Ponzi scheme, they surround the building, and the culprit disappears in a locked room.
One of the better This Week stories.
Reading Ellery Queen 
Oh, “locked room” makes me think of the story where everything is turned around in one or another sense, such as a painting hung on the wall has been flipped to face towards the wall, and a rug has been turned face-down.
The solution that Ellery realizes is that the deceased is a member of the clergy and wearing a clerical collar. So the collar is made to appear just a part of the obsessive reversing. And that obscures his identity and thus the motive. (I see this doesn’t solve the locked-room aspect. But that is beyond my recollection.)
Mitch4, I think you posted this one in error here. Your analysis has to do with one of the Golden Age EQ novels. I won’t say which one so as not to spoil it for new readers, but I’m sure you know which one.
Right, I can’t see now how I thought this was connected!