Rising concern about the health of the global economy sent the markets tumbling to a sharply lower close with the Dow collapsing 272 points to 16,719. Nasdaq plummeted 69 points to 4,385.

On the upside

The bankruptcy filing of GT Advanced Technologies (Nasdaq: GTAT) lifted shares of rival scratch resistant sapphire glass maker Rubicon Technology (NYSE: RBCN).

Bargain hunters lifted shares of Vivint Solar (NYSE: VSLR). 

FBR Capital upgraded Alcobra (Nasdaq: ADHD) from a Market Perform rating to an Outperform rating.

On the downside

Delta Airlines (NYSE: DAL) terminated its contract with Innovative Solutions & Support (Nasdaq: ISSC) for cockpit upgrades to its fleet of MD88 and MD90 aircraft.

On Track Innovations (Nasdaq: OTIV) will sell $50 million worth of stock and warrants.

Moody’s downgraded IAMGOLD’s (NYSE: IAG) corporate family rating from Ba3 to B1.

In the broad market, declining issues outpaced advancers by a margin of nearly 7 to 2 on the NYSE and by more than 4 to 1 on Nasdaq. The broader S&P 500 plunged 29 points to 1935. Bitcoin slipped $6 to $327.