NEW YORK ( TheStreet) -- Stock futures were falling, pointing to an extension of the S&P 500's steepest one-month decline in over a year on concern China's economy is sharply weakening amid liquidity concerns while New York Federal Reserve President William Dudley criticized the bank's monetary policy. Dudley, a Federal Open Market Committee voting member, called on the Fed to be more aggressive in its bond-buying program, saying the central bank has failed to reach its inflation and employment targets. Futures for the S&P 500 were falling 15.75 points, or 17.13 points below fair value, to 1,568.25. The Shanghai composite plummeted 5.3% on Monday, its most severe single-session drop in nearly four years as the People's Bank of China indicated the country's largest banks should limit risky loans to strengthen their balance sheets. Stocks with heavy exposure to the world's second largest economy were sinking. For instance, Yum! Brands ( YUM) was falling 0.67% to $68.52. Caterpillar ( CAT) was behind by 1.48% to $81.89. The index has slid 2.35% so far this month and is on track for its most severe monthly retreat since May of last year. The S&P is down more than 4% from its record intraday high reached on May 21, driven by expectations that the Fed is poised to taper its bond-buying program that has helped the gauge climb more than 100% from its March 2009 lows. Facebook ( FB) shares were falling more than 1.5% to $24.15 after the company said a bug in its system caused contact information for 6 million users to be inadvertently exposed. Apple ( AAPL) shares were slipping 1.45% to $407.50 after analysts at Jefferies reduced their price target on the tech giant to $405 from $420 with a hold view, writing that the company is likely to reduce that pace of its iPhone production amid high inventory levels, and as it gets ready for the potential launch of the iPhone 5S in September and iPhone 6 in the coming year. Tenet Healthcare ( THC ) is buying Vanguard Health Systems ( VHS ) in a deal that further consolidates the U.S. healthcare industry in the wake of the passage of the Affordable Care Act (ACA), which was mostly upheld by the U.S. Supreme Court about a year ago. Tenet shares were popping 5.85% to $44.30 in premarket trading, while Vanguard was soaring more than 67% to $20.66. Futures for the Dow Jones Industrial Average were tumbling 136 points, or 144.4 points below fair value, to 14,575. Futures for the Nasdaq were slipping 22.25 points, or 27.29 points below fair value, to 2,842.75. The Dallas Fed general business activity index for June is expected at 10:30 a.m. EDT. The index stayed negative in May but rose five points to minus 10.5 last month. Dallas Federal Reserve Bank President Richard Fisher at 1 p.m. is expected to speak about monetary policy in London. The FTSE in London was falling 1.27%, while the DAX in Germany was down 1.1%. The Hong Kong Hang Seng index settled off 2.22% and the Nikkei 225 in Japan closed down 1.26%. The benchmark 10-year Treasury was tumbling by 1 1/32, pushing the yield up to 2.659%. The dollar was tacking on 0.48% to $82.72 according to the U.S. dollar index . August gold futures were falling $12.20 to $1,279.80 an ounce. August crude oil futures were down 25 cents to $93.44 a barrel. Follow @atwtseWritten by Andrea Tse in New York >To contact the writer of this article, click here: Andrea Tse.