10 things you need to know before the opening bell

Good morning. Here's what you need to know.

Turkey shot down a Russian fighter jet near the Syrian border. Turkey said it shot down a Russian Su-24, claiming that it was in the country's airspace. It said the plane, which was carrying two people, did not respond to multiple warnings. Russia confirmed that the plane belonged to its military, though it contended that the plane was in Syrian airspace. Russia also said the plane was attacked from the ground, while Turkey said it was shot down by a Turkish F-16. The pilots reportedly ejected from the aircraft.

Markets are falling. Europe is in the red with Britain's FTSE 100 down 1.0%, Germany's DAX down 1.1%, France's CAC 40 down 1.7%, and Spain's IBEX down 1.7%. US futures are lower with Dow futures down 69 points and S&P futures down 9 points.

Bank of England says low interest rates will linger 'for some time.' In a testimony to lawmakers in London on Tuesday, BoE Governor Mark Carney said, "The question in my mind is when is the appropriate time for interest rates to increase." He reiterated that rates would nevertheless remain low "for some time" and that the pace of rate hikes would be "limited."

Bill Ackman cranks up his bet on Valeant. Pershing Square Capital, the hedge fund led by Bill Ackman, disclosed that it increased it's stake in controversial drug giant Valeant Pharmaceutical to 9.9% from 5.7%. His new 14,644,618 share stake is a combination of 2,144,618 shares of common stock and American-style call options, which he can exercise and get 12,500,000 shares. He also sold European-style call and put options, presumably to help finance the purchase.

Carl Icahn makes a big bet on Xerox. Carl Icahn disclosed that he bought a 7% stake in Xerox, a purchase of 72.2 million shares worth $86.5 million. In a regulatory filing, he said he acquired the position "in the belief that the shares were under valued," and that he intends to "have discussions with representatives of the Issuer's [Xerox's] management and board of directors relating to improving operational performance and pursuing strategic alternatives, as well as the possibility of board representation."

Tiffany's whiffs. Jewelery retailer Tiffany's Q3 was weak. Comparable store sales climbed by just 1%, which was far short of the 3.3% expected by analysts. The company earned $0.70 per share, which was below the $0.75 expected. "As expected, the strong US dollar continued to put pressure on our financial results, specifically from the translation of non-U.S. sales into dollars and on foreign tourist spending in the US," CEO Frederic Cumenal said. "In addition, we believe that volatile, uncertain economic and market conditions in the US and other regions are affecting consumer spending, causing us to maintain a cautious near-term outlook."

German business confidence improves. The Ifo institute's business climate index unexpectedly climbed to 109.0 in November from 108.2 in October. "In one line: Solid," Pantheon Macroeconomics' Claus Vistesen said.

Janet Yellen warns against an 'overly aggressive increase in rates.' In a letter to consumer advocate Ralph Nader, Federal Reserve Chair Janet Yellen discussed the importance of a cautious approach to monetary policy, including the tightening of policy with interest rate hikes. "An overly aggressive increase in rates ... would at undercut the economic expansion, necessitating a lasting return to low interest rates," Yellen said.

Goldman Sachs thinks stocks are going nowhere in 2016. "We forecast the S&P 500 index will tread water for a second consecutive year in 2016," Goldman Sachs' David Kostin said. "Our year-end 2016 target of 2100 represents a 1% price gain from the current index level (2089), which itself is just 1% above the year-end 2014 level of 2059. Including dividends, we expect the total return in 2016 will equal 3%." Kostin notes unfavorable conditions include tighter monetary policy, contracting P/E multiples, and plateauing profit margins."

Economic data. At 8:30 a.m. ET, we'll get the second estimate of Q3 US GDP. That'll be followed by the September S&P Case-Shiller Home Price index report at 9:00 a.m. ET. At 10:00 a.m. ET, we'll get the November consumer confidence report from the Conference Board. Read BI's complete preview of the data in the Monday Scouting Report.