When Jeremy Grantham entered the investment business in the 1960s, he brought the thrifty Yorkshire values he had been raised with. While other money managers focused on blue chip stocks, he studied stock market history and constructed the first indices for small-cap and value stocks. Charting their ebb and flow, he saw the powerful force that would become central to his investment philosophy: mean reversion, 'the heartbreaking principle that good times always revert back to more boring, more ordinary times.' In the early 1970s Grantham launched one of the first S&P 500 index strategies. Soon after, he cofounded GMO, which became the first firm to use a computer for investment analysis. In the late 1990s he acquired notoriety as a 'permabear' for refusing to buy into dotcom mania. Clients left in droves, but he was vindicated when the bubble burst in 2000. Yet while his wealth grew, so did his alarm at the disastrous consequences of short-term thinking for both investors and for the planet, and he has directed nearly all his wealth to environmental protection. Written with the bestselling financial historian Edward Chancellor, The Making of a Permabear is replete with investment insights and provides a candid insider's tour of the booms and busts of the past half century.