Opportunity-Cost Decision Rule
Compare a held-out gain with what tied-up capital could earn elsewhere
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 4
- Confidence
- 94%
The Opportunity-Cost Decision Rule evaluates a choice by including what the committed resources cannot do elsewhere. Thorp illustrates it with a homeowner who rejected a $3 million offer while holding out for $3.25 million. A housing downturn then trapped the capital for a decade, during which alternative stock-market gains could have dwarfed the extra $250,000. The mechanism is to compare the incremental upside from waiting with the time, liquidity, and compounding sacrificed by waiting. Thorp also observes that people often see these trade-offs more clearly for friends than for themselves, so taking an outside view helps counter discomfort, inertia, and attachment to a target price.
Origin
Thorp explains the rule through a friend's decision around 1989 or 1990 to hold a house for a higher sale price.
Core principles
- 01Count the return forgone while capital stays tied up
- 02Judge the whole decision horizon rather than the visible gain
- 03Separate emotional attachment to a price from economic value
- 04Use an outside view when personal involvement clouds judgment
How to run it
- 1
Define the immediate choice
Record what you can receive or change now and the extra benefit you hope waiting will produce.
Pro tip Express the hoped-for gain as an increment over today's available outcome.
Watch out Do not treat a desired price as value merely because you chose it.
- 2
Price the waiting period
Estimate how long resources could remain committed and what credible alternatives might earn during that time.
Pro tip Use a range when the waiting period or alternative return is uncertain.
Watch out Ignoring compounding makes a long delay look artificially cheap.
- 3
Compare total outcomes
Set the hoped-for incremental gain against the foregone return, reduced liquidity, and delay.
Watch out Do not compare only the two sale prices.
- 4
Take the outside view
Ask what you would advise a friend facing the same facts, then use that answer to challenge inertia.
Pro tip Invite a disinterested person to test your assumptions.
Watch out Personal discomfort can make an economically obvious transition feel impossible.
In the wild
Thorp's friend could have sold his house for about $3 million but wanted $3.25 million. After the housing downturn, it took 10 years to obtain his price, while the tied-up capital missed a strong decade in stocks.
→ Thorp estimates that seeking an extra $250,000 may have cost the owner $6 million to $8 million.
Common mistakes
Counting only the visible gain
The extra sale proceeds look attractive until the return forgone during the delay is included.
Letting discomfort preserve the status quo
People can recognize a better transition for somebody else while resisting the same move themselves.
Is it for you?
Best for
People deciding whether to sell an asset, leave a stagnant role, or redeploy committed capital.
Not ideal for
Decisions where the alternatives cannot be compared even approximately or non-financial values dominate.
From the transcript
“He didn't understand that by holding out for the extra money he was tying up his capital.”
“He was having an opportunity cost and he was missing maybe a multiple of two or three in the stock market over the next decade.”
From the episode
#604: Master Investor Ed Thorp on How to Think for Yourself, Mental Models for the Second Half of Life, How to Be Inner-Directed, How Basic Numeracy Is a Superpower, and The Dangers of Investing Fads
Ed Thorp