If there was a feeling of calm recently as stocks reached all-time highs, that was an illusion. One way to see the frayed nerves is to look at implied volatility on the S&P 500. Five years ago, as the index was grinding out new highs week after week and the economy globally was humming along, implied volatility remained low. Prices are back at record highs, but implied vol is more akin to 2010 and 2011 when growth scares, wobbly banks and an uncertain path out of the GFC still held sway.