When I began stockbroking in 1984, our four‑person research team used a CRT monitor and a bulky book to program valuations for debentures, giving us a half‑penny edge over jobbers; a 40‑year career has seen markets stretch to levels only seen before the 1999‑2000 dotcom bubble.

The story starts with JK Galbraith’s 1928 warning of a “mass escape into make‑believe,” followed by the 1929 crash where prices fell more than 85%; before that, equities were valued by dividend yield or balance‑sheet assets, and Graham and Dodd’s 1934 *Security Analysis* defined a sound investment as one promising safety of principal and an adequate return.

Fisher’s 1958 *Common Stocks and Uncommon Profits* introduced growth investing, while Fisher later suggested a valuation heuristic of earnings multiplied by 8.5 and twice expected growth; the 1972‑73 “Nifty Fifty” bubble peaked at 50× P/E before 26.9% UK inflation in 1975 burst it, leading to 40% US and 73% UK market declines.

Later, Phillips & Drew used Excel to spot asset‑heavy bargains, a practice Buffett called ‘cigar‑butt’ investing; the tech bubble of 2000 showed the limits of simple DCF and P/E ratios, and Goodhart’s Law warns that when earnings become the target, the measure loses its reliability.