The index rose sharply in January 2018, extending one of its longest monthly winning streaks, only to fall 4% in February 2018 during a month of extremely high volatility, including a day in which the VIX doubled. It was the first monthly decline in 11 months. In the third quarter of 2018, the index posted its best quarter since 2013. However, the index fell 11% in the month of December 2018, its worst December performance since the Great Depression. The index fell 6% in 2018, its worst year in a decade.