US STOCKS-S&P futures fall as Apple forecast hits tech

(Updates to show futures falling after the close)

NEW YORK, Jan 22 (Reuters) - U.S. S&P 500 stock index futures slid after the closing bell on Tuesday as a weaker-than-expected forecast by Apple Inc. (AAPL.O) hit shares of major technology companies.

S&P 500 futures SPc1 were down 8.20 points, below fair value, a mathematical formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. (Reporting by Caroline Valetkevitch; Editing by Jan Paschal)