Martin Scorsese and Roger Ebert Talking Movies

Most of you will have heard of Martin Scorsese (duh), but perhaps not everybody will have heard of Roger Ebert. If you’re looking to improve your writing, read his reviews.

His reviews are also a great way to pick what to watch on pretty much any night. Also watch his reviews with Gene Siskel.

But for today, enjoy this conversation between two people who knew just a little bit about movies

Understanding Arbitrage

Part 1 and Part 2 here. I’d recommend you read those before you start this one.

Now, what if at the end of the academic year, you find yourself without a job offer? We all hope and pray that this doesn’t happen to anybody, but the sad reality is that there will always be such cases.

What could be done?

What I am about to describe doesn’t actually happen in any college that I know of, but it helps me build my story, so let’s go with it for the moment:

What a university could do is that it could hire the services of a placement agency. Said placement agency would take on the responsibility of getting these students placed in one firm or the other. These wouldn’t be glamorous jobs, of course, and they wouldn’t be high-paying ones. But hey, at that stage, any job offer is a good offer – and you could always try and shift as soon as possible into a better job, no?

The placement agency wouldn’t do this for free, of course. The college would have to pay the placement agency for each student placed.


Here’s the interesting part, though. It is quite likely that the placement agency would be taking a fee from the firm in which this student got placed. That is, the placement agency gets a fee from the college, but it also gets a fee from the firm.

(There are variants, of course. But we’re talking Zomato, Uber, Dunzo and old school real estate agents and all that. Middlemen, essentially. The equilibrium of who pays, and how much, and why are all excellent questions for an intermediate micro class.)

So what is the placement agency doing? In the language of the financial markets, it is engaging in arbitrage. Arbitrageurs make markets more efficient, by connecting supply and demand. The type of supply and demand that wouldn’t have been able to connect otherwise.

The student that didn’t get placed, and the firm that wanted a new employee hadn’t been able to meet so far, and the placement agency facilitated this deal. We’re talking economics, of course, and the placement agency therefore deserves a fee for providing this service.


This fee can be collected in two ways. First, the way that I just described above: take a flat fee from both sides of the transaction. Or, think of a bank. What does a bank do? It connects people who are willing to loan money to people, with people who are looking for a loan. The bank acts as the middleman, and offers a lower rate of interest to depositors. It also charges a higher rate of interest to people who want to take a loan.

This is known as the bid-ask spread. The middleman bids a lower rate while buying, and asks for a higher rate while selling.


An efficient market is one in which there are no arbitrage opportunities. Or in the language of the economist, an efficient market is one in which there are no search costs. It’s mostly the same thing. I have fixed deposits in the bank that pay me a painfully low rate of interest. In my neighbourhood is a person who has taken a loan from the same bank in which I have my fixed deposit. She is being charged an eye-wateringly high rate of interest.

In effect, I am loaning my money to her. Because I do not know of her existence (nor she of mine), we both use the bank to “complete” the transaction. The difference between the rate of interest I get and she is charged is what pays for the rent of the bank, its employees salaries and so on.

(By the way, what if the bank gives out a new loan to another person before my neighbor has repaid hers? Leverage!)


Real estate agents made the real estate market more efficient than it would have been otherwise, but their margins were so high, that Magic Bricks, and Housing.com and their ilk had a reason to enter and promise lower commissions. So also Uber, so also Airbnb, so also (think about it) Amazon.

Perfect competition, which we learn about in microeconomics, is best thought of as an always ongoing process, not as a static equilibrium. One aspect of which is better, more efficient arbitrage. That’s not how the textbooks do it, and more’s the pity.

Anyways, arbitrage is a good thing, because it makes markets more efficient in two ways:

  1. It makes trades happen that wouldn’t have taken place otherwise
  2. Competition between arbitrageurs drives the “market-making” fee downwards, making more trades happen at cheaper rates.

A truly efficient market is one in which there are no further arbitrage opportunities, and market-maker fees can’t possibly be any lower. No, as it were, dollar bills lying in the streets. See if the joke now makes sense.


So, over the past three days, we’ve learnt about the following:

  1. Forwards markets
  2. Hedgers
  3. Speculators
  4. Arbitrageurs
  5. Efficient markets

Next week (for there is only so much finance we can take at a time) we’ll get back to trying to understand finance, beginning Monday.

Optional homework: watch (and try to make sense of) Arbitrage. And if you want an example of how to write well, read this review of the movie – whether you watch it or not.