NEW YORK - Stock index futures slid on Tuesday as concerns that the global recession was worsening fueled a global equity rout, and investors worried that efforts to stem the downward spiral and stabilize the financial system may not be enough.

* The diminishing appetite for riskier assets sunk stocks in Asia overnight, while in Europe benchmark indexes were down more than 2 percent.

* S&P 500 futures fell 18.10 points, and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures declined 154 points, and Nasdaq 100 futures were off 32.25 points.

* A precipitous slide on Wall Street, a day after the Presidents Day holiday, would put U.S. stocks on the cusp of retesting the bear market lows hit late November.

(Reporting by Ellis Mnyandu; Editing by Theodore d'Afflisio)