Citi's Panic / Euphoria model is closing in on 'euphoria,' which means investor complacency is very high.

According to Citi, the model's components include "NYSE short interest ratio, margin debt, Nasdaq daily volume as % of NYSE volume, a composite average of Investors Intelligence and the American Association of Individual Investors bullishness data, retail money funds, the put/call ratio, CRB futures index, gasoline prices and the ratio of price premiums in puts versus calls."

Source: Citi, Business Insider