WACC vs Opportunity Cost
high confidence — compiled with source citation from the investment brain.
WACC vs Opportunity Cost
WACC vs Opportunity Cost
Both warren-buffett and aswath-damodaran agree on what a discount rate is — an opportunity cost, the return foregone on the next-best investment of equal risk. They disagree sharply on how to build the number: Buffett uses a single, judgment-based rate and pours his analytic effort into the cash flows; Damodaran builds the weighted-average-cost-of-capital machinery, estimating a cost of equity and cost of debt and weighting them by the financing mix.
The shared premise
Damodaran states the common ground plainly: "For investors in companies, the cost of capital is an opportunity cost in the sense that it is the rate of return that they would expect to make in other investments of equivalent risk." This is exactly the notion behind Buffett's 1980 "hurdle rate," which he defines as "the return on equity that must be achieved by a corporation in order to produce any real return for its individual owners."
Buffett's single-rate view
Buffett's illustrative math uses one rate across very different businesses. In the 1991 media discussion he values a growing media annuity and a "bob-around" cyclical at the same 10%: "a discount rate of 10% was used to determine the present value of that earnings stream", and he adds the principle behind the single rate — "Dollars are dollars whether they are derived from the operation of media properties or of steel mills." The implication is that risk differences belong in the cash-flow assumptions (growth, durability), not in a different discount rate per industry.
His deeper objection is to the risk input the WACC machinery rests on — beta, estimated from price volatility. On history-based models he is blunt: "Our advice: Beware of geeks bearing formulas." And in 2011 he defines risk away from volatility entirely: "The riskiness of an investment is not measured by beta … but rather by the probability – the reasoned probability – of that investment causing its owner a loss of purchasing-power over his contemplated holding period." A currency-denominated instrument can have "beta … zero, but their risk is huge." This is the same definition of risk the corpus treats under risk-vs-uncertainty and permanent-loss-of-capital.
Damodaran's machinery
Damodaran's answer is the cost-of-capital weighted average — cost of equity from a riskfree rate plus an equity-risk-premium scaled by beta, cost of debt from a riskfree rate plus a default spread, weights from market values. His defense of the apparatus is that a public-market discount rate should carry only undiversifiable market risk, leaving company-specific risk to the cash flows: "with a public company, the discount rate is a vehicle for reflecting macro economic or market risks that cannot be diversified away, company specific risk get adjusted for in expected cash flows."
Crucially, Damodaran also warns against loading the rate with personal hopes and fears — a warning that converges with Buffett's skepticism even if their methods do not: the cost of capital "is not a receptacle for your hopes and fears, where you respond to discomfort with uncertainty by increasing your discount rate."
The real disagreement
Both men would agree the discount rate is an opportunity cost, not a target return, and that risk
should not be double-counted. The genuine fork is how risk is measured and priced: Damodaran
relies on beta and the CAPM-derived equity-risk-premium to make the rate defensible and
comparable across firms; Buffett regards price-volatility-based risk as measuring the wrong thing
and prefers one conservative rate, spending his effort making the cash flows honest instead.
Neither position is falsified by the other — which is why this page is marked
contested: true and why the two views are recorded here as dated opinions rather than reconciled.
See also
Sources
damodaran/markdown/costofcapital.mdberkshire-hathaway/Letters-Markdown/1980 - Letter to Shareholders.mdberkshire-hathaway/Letters-Markdown/1991 - Letter to Shareholders.mdberkshire-hathaway/Letters-Markdown/2008 - Letter to Shareholders.mdberkshire-hathaway/Letters-Markdown/2011 - Letter to Shareholders.md