Bruce Greenwald

Bruce Greenwald is an American economist and educator, born in 1946. He studied at the Massachusetts Institute of Technology, where he completed a doctorate in economics in 1978, and also holds a public affairs degree from Princeton. He taught at Bell Laboratories, Harvard Business School and the Wharton School before joining Columbia Business School in 1991.

At Columbia he held the Robert Heilbrunn Professorship of Finance and Asset Management and served as academic director of the Heilbrunn Center for Graham and Dodd Investing, the institutional home of the value tradition that Benjamin Graham and David Dodd began teaching there in the 1920s. He taught the school's value investing course for many years and became emeritus in 2019.

His academic work sits in a different field from his teaching reputation. With Joseph Stiglitz he published a series of papers on markets with imperfect information, including the result now known as the Greenwald-Stiglitz theorem, which showed that when information is imperfect or markets incomplete, competitive equilibria are generally not efficient even in the constrained sense. That work is part of the body of research for which Stiglitz later shared a Nobel Memorial Prize.

What reached investors was the pair of books he wrote with Judd Kahn. Value Investing: From Graham to Buffett and Beyond, published in 2001, set out a three-layer approach to valuation ordered by how reliable each layer is. Competition Demystified followed in 2005 and argued that business strategy, stripped of its complications, is almost entirely a question about barriers to entry.

Greenwald's valuation method is organised by reliability rather than by completeness, which is its distinguishing feature. He works in three layers. The first is asset value, estimated as what it would cost to reproduce the assets of the business today; this rests on the balance sheet and is the most dependable figure available. The second is earnings power value, which takes current sustainable earnings, assumes they continue indefinitely with no growth at all, and capitalises them at the cost of capital. The third layer is the value of growth, which he treats as the least reliable and handles last.

The reason for that ordering is an argument about competition. Growth requires investment, and investment in a business with no barrier to entry earns roughly the cost of capital, because competitors enter until it does. Growth in that situation consumes capital and creates nothing. Growth is only worth paying for when it happens behind a barrier that stops competitors from competing the returns away, which means the strategic question has to be settled before the growth assumption can be used at all.

That leads to the comparison he treats as diagnostic. If earnings power value is well above asset value, the business is earning more than the assets alone would justify, and something must be preventing competitors from entering and eroding the gap. If it is not, there is no evidence of a franchise, and the analyst should be sceptical of any story that claims one.

Competition Demystified takes the same insight into strategy. He argues there are essentially three durable sources of advantage: a supply advantage such as proprietary technology or a genuine cost edge, a demand advantage arising from customer captivity through habit, switching costs or search costs, and economies of scale where a large incumbent spreads fixed costs over a base a new entrant cannot match. Most other claimed advantages, in his account, are capabilities competitors can acquire. He also argued that advantage is usually local, holding within a specific market or geography rather than everywhere at once, and offered two observable tests: stable market shares over long periods, and returns on capital that stay high without being competed down.

The earnings power value method gave analysts a way to value a company without projecting growth at all, which is now a standard first step in conservative valuation work and a common check against a discounted cash flow that has become too dependent on its terminal assumptions.

Competition Demystified supplied much of the working vocabulary used when investors discuss moats. The reduction of durable advantage to supply, demand and scale, and the market-share and returns tests that go with it, turned a qualitative judgement into something a reader can check.

Through the Columbia value investing course he taught a large number of practising investors, which is how the framework spread through the profession alongside the books.