One definition of a bear market says markets are in bear territory when stocks, on average, fall at least 20% off their high.
But 20% is an arbitrary number—just as a 10% decline is an arbitrary benchmark for a correction.
Several leading stock market indexes around the globe endured bear market declines in 2018.
US stocks suffer worst week in a decade
Earlier this week, the US Federal Reserve lifted the interest rate and signalled that it would continue to rise next year, albeit at a slower pace.
BBC 21 December 2018