US STOCKS-Futures drop on global economy concerns, merger doubt
* Bank of America gains in premarket after results
* Shire shares tumble as AbbVie reconsiders bid
* PPI, Retail sales data due
* Futures off: Dow 111 pts, S&P 16.5 pts, Nasdaq 29 pts (Updates prices, adds premarket movers)
By Chuck Mikolajczak
NEW YORK, Oct 15 (Reuters) - U.S. stock index futures dropped on Wednesday as selling resumed on worries over the health of the world economy, ahead of a slew of data and corporate earnings.
The benchmark S&P 500 had eked a tiny gain at the close a day earlier following three sessions of declines spurred by concern over the potential spread of Ebola, the impact of global economic weakness on U.S. earnings and plunging oil prices.
The S&P has lost 6.6 percent since its Sept. 18 record closing high and is now up just 1.6 percent for the year, while the Dow is down 1.6 percent since Dec. 31.
Futures were little changed earlier in the day before dropping steeply in heavy trading, reflecting a recent jump in volatility in the equity markets. Continuación...