Economist: Flying high - Are stockmarkets in a bubble? March 10, 2017 by Garret Vreeland in Economics, Politics By historical standards, valuations in the American market are worryingly dear. The cyclically adjusted price-earnings ratio, which averages profits over ten years, is just under 30, according to Robert Shiller of Yale University. Only twice has it been higher—in the late 1990s, during the internet boom, and just before the crash of 1929.Related to previous.