The markets reversed course in late afternoon trading to close lower with the Dow plummeting 167 points to 16,346 as crude oil prices fell below $33 per barrel. Nasdaq plunged 45 points to 4,643.

On the upside

Harvard Apparatus Regenerative Technology (Nasdaq: HART) scheduled initial implant surgeries of bioengineered organs on January 22 and February 2.

Bargain hunters lifted shares of Qunar Cayman Islands (Nasdaq: QUNR).

Shares of MakeMyTrip (Nasdaq: MMYT) extended its gains.

On the downside

Investors continued to lock in profits on Weight Watchers International (NYSE: WTW).

Profit taking weighed down shares of Auris Medical Holding (Nasdaq: EARS) for the second day.

Conn's (Nasdaq: CONN) stock continued to fall.

In the broad market, advancing issues outpaced decliners by a margin of nearly 7 to 3 on the NYSE and by more than 5 to 2 on Nasdaq. The broader S&P 500 plunged 21 points to 1,922. Bitcoin lost $1 to $452.