Rational Pricing

Categories: Financial Theory

Did you know that assets can rationally price themselves? Well...now you do.

Rational pricing is the idea in financial economics that prices always end up leveling out to the “true” price, free of arbitrage opportunities. Let’s take a look at one asset selling in two markets to see what we mean by this.

If the stock Flubber is selling for $50 per share on the New York Stock Exchange and for $48 on the Hong Kong Stock Exchange, that’s an arbitrage opportunity. Investors will see this difference, and buy up the $48 stocks from Hong Kong SE, selling them for $50 on the New York SE, for a profit of $2 per stock. After Flubber is all arbitraged-up, the price difference disappears.

This is rational pricing at work, with prices of the same good equalizing itself. If the U.S. found all of the same goods on AliExpress for cheaper than on Amazon, causing a flock of customers to AliExpress, the cost of goods on AliExpress would go up from the increase in demand, and the price of goods on Amazon would go down from the sudden drop in demand. Eventually, the prices of the same stuff on the two platforms would be equal.

Arbitrageurs are only being rational, you know?

Related or Semi-related Video

Econ: What are Rational Expectations?5 Views

00:00

And finance Allah shmoop what are rational expectations Alright people

00:07

Well life can change pretty quickly One day you're the

00:10

CEO of a Wall Street hedge fund making a fifteen

00:13

twenty thirty million dollars a year or more than one

00:16

bad experience with a cursive monkey paw and poof You're

00:19

the break dance guy on the subway busking for ninety

00:22

bucks a day in tips Yeah I guess you shouldn't

00:24

have wished to become a better dancer Well but given

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that you can never tell exactly what will happen in

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the future how do you decide what to do Day

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today Lt'll economists have a model they use It's called

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rational expectations The theory assumes that people make economic decisions

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based on their reasonable assumptions about what's gonna happen in

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the future Folks look at their current situation and it

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what's happened in the past and from there they make

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educated guesses about what's likely to happen in the future

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Well these expectations in turn become the bases or foundation

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for their decision making Gas prices have been low forest

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long as you can remember so you don't care much

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about fuel efficiency when you go out and buy a

01:01

car So you go for the ten miles a gallon

01:04

Hummer Rational expectation Until militants take over Saudi Arabia's largest

01:09

oil production field gas prices spike Now you're paying two

01:12

hundred dollars a month to fill your gas tank Remember

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a lot of economic activity is based on what people

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think will happen in the future Will people borrow money

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planning to pay it back years In the future they

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buy houses with thirty year mortgages They choose college majors

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with an eye toward a forty year career Well aside

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from philosophy majors maybe people make decisions based on what

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they think the future will be like right Robert Lucas

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won the Nobel Prize in nineteen ninety five for his

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work on the theory of rational expectations This guy well

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quick fun fact When Lucas Scott divorce from his wife

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Rita in the late nineteen eighties the divorce agreement included

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a stipulation that she would get half of his Nobel

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Prize winnings if he ever won the award However the

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Klaus had an expiration date of Halloween nineteen ninety five

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He officially won his prize on October tenth nineteen ninety

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five just under the wire So okay most of us

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don't rationally expect our spouse is to win half a

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Nobel Prize kind of money but most of us are

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just happy if they remember to put down the toilet

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seat But yeah we do make other long term decisions

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based on what we think we'll be able to make

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on an ongoing basis in your hedge fund days You

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wouldn't think twice about taking on a five million dollar

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mortgage for a vacation place in Bermuda However you never

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take on that responsibility If you knew that your monkey

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paw wish was going to go sideways and you know

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leave you with eighteen thousand dollars in annual salary your

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rational expectations impact your big long term money making decisions

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They also play into your smaller data day decisions Even

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deciding what you're going to have for dinner relates to

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how much money you expect to make in the near

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future Will the precursor version of you while you then

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might have gotten the nine course tasting menu It hearsay

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with the caviar Black Australian truffles flog raw and wagyu

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beef The bill would run six hundred bucks a person

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but you can afford it So like who cares The

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post curse break dance version of you might decide to

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go with the Junior Bacon cheeseburger off Lindy's Value menu

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which costs a buck ninety nine Yeah that's all you

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can afford But the rational part of rational expectations assumes

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that your predictions will stem from past experience Unless you've

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had trouble with cursing objects before it's unlikely that you'll

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see the bad wish scenario coming Given that you've been

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a fifteen million dollars plus a year hedge fund manager

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for twenty years at five million dollars vacation home or

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good seems very manageable There's no reason to expect your

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job to change The reasonable assumption is that you'll keep

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your fat salary for the foreseeable future Well dinner's at

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per se a vacation spots in Bermuda Yeah but then

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you wandered into that dingy curiosity shop on your last

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trip to Hong Kong and asked the man behind the

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counter if he had anything really interesting Then he started

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stroking his beard and well on the bright side you

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always wanted to be able to do the worm Yeah 00:03:55.178 --> [endTime] Yeah

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