I first publicly discussed Walter’s remarkable record in 1984. At that time “efficient market theory” (EMT) was the centerpiece of investment instruction at most major business schools. This theory, as then most commonly taught, held that the price of any stock at any moment is not demonstrably mispriced, which means that no investor can be expected to overperform the stock market averages using only publicly-available information (though some will do so by luck). When I talked about Walter 23 years ago, his record forcefully contradicted this dogma.
