In general market terminology, any asset down 20% from its most recent high or from a particular period like a quarter or year-end is defined as having entered a bear market. The S&P 500 was hovering at around 3,810 on Friday afternoon, down 20% from its December finish of 4,767. Nasdaq, which includes top technology names such as Amazon, Apple, Netflix and Google, was at 11,042, down 29.2% from last year’s close of 15,645.