Monday, September 12, 2011

There's no such thing as a $20 bill lying on a sidewalk.

The title of this post contains a truth, but I think it could stand to be spruced up a little. I will suggest what I think is a better way of putting it at the end of this post.

I was walking to brunch the other day with my wife when we passed what appeared to be several dollar bills on the sidewalk. "Leave 'em," I said, "they can't really be there." (True story -- but then I went back and picked them up.)

I also was walking with economist Thomas McQuade once when we literally found a $20 bill on the sidewalk.

I also worked for a firm that spent the entire trading day scooping up $20 bills from sidewalks of the the financial markets, especially the options market and the pending merger market. Now, the truth contained in the statement in the post title is this: we had to be really, really fast to get those twenties. There were plenty of other people scanning the sidewalk for them. We invested millions in proprietary software, high-speed feeds, and really smart traders. These opportunities lasted only seconds, and we had to be able to seize them during that instant they were yet unnoticed by others.

I think the more correct formulation is "A $20 bill on the sidewalk won't be there for long."


  1. Or: there have to be enough twenty dollar bills on the sidewalk to provide a normal return to the activity of scanning for them. If there were fewer than that, paying attention wouldn't pay so more would accumulate. If there were more than that, scanning would pay above-normal returns, there would be more scanning and the number not picked up would fall.

  2. Right. It's funny because your formulation seems to obvious, and yet a lot of economists keep acting as if they believe the original proposition in your post title. (FYI I found a dollar the other day in the parking lot.)


Current review queue

Pearce: British Journal for the History of Philosophy Deneen: The American Conservative Chao-Reiss: Computing Reviews