From Bloomberg:
It’s no secret that U.S. stocks are overvalued. After eight consecutive years of gains — we’re now into the ninth — it would make sense that the S&P 500 Index would have above-average valuations based on almost every measure.
Legitimate arguments can be made that U.S. stocks deserve these prices for many reasons, including low interest rates, low inflation, slower growth everywhere, higher profit margins, and a diverse and mature economy.