* Futures up: Dow 211 pts, S&P 25.75 pts, Nasdaq 70 pts
By Tanya Agrawal
Feb 16 (Reuters) - U.S. stock index futures were higher on Tuesday as Brent crude oil prices hit a 12-day high after four of the world's largest producers agreed to freeze output.
* Oil prices, which has been on a roller-coaster ride this year, rose more than 1 percent after the move by Russia, Saudi Arabia, Qatar and Venezuela to tackle a global supply glut.
* Besides oscillating oil prices, investors have also been concerned regarding a China-led slowdown in the global economy.
** The S&P 500 remains down more than 8 percent since the beginning of the year, even though Chinese stock markets were closed during last week's selloff in risky assets.
* Earlier on Tuesday, Chinese stocks closed with their biggest daily percentage gain in more than three months. Remarks by Premier Li Keqiang were interpreted as hinting at more stimulus for the world's second-biggest economy.
* Investors will also be keeping an eye on speeches by the presidents of the Philadelphia Fed, Minneapolis Fed and Boston Fed, who will give their views on the economy on Tuesday.
* Investors already nervous about the health of the global economy have found little relief in U.S. corporate reports. S&P 500 companies' fourth-quarter earnings are expected to have fallen 3.9 percent from a year earlier.
* Shares of ADT surged 50.80 percent to $40.52 premarket after private equity firm Apollo Global Management agreed to buy the electronic security services provider for $7 billion.
* Freeport-McMoRan was up 6.7 percent at $5.9 after the copper-miner agreed to sell a stake in one of its mine to Sumitomo Metal Mining.
Futures snapshot at 7:24 a.m. EDT (1224 GMT):
* Dow e-minis were up 211 points, or 1.33 percent, with 90,213 contracts changing hands.
* S&P 500 e-minis were up 25.75 points, or 1.39 percent, with 585,866 contracts traded.
* Nasdaq 100 e-minis were up 70 points, or 1.75 percent, on volume of 89,429 contracts. (Reporting by Tanya Agrawal in Bengaluru; Editing by Savio D'Souza)