* Schlumberger earnings drop, but beat estimates
* Microsoft, Amazon results disappoint late Thursday
NEW YORK, July 24 (Reuters) - U.S. stock index futures rose slightly on Friday despite disappointing results from Microsoft Corp and Amazon.com Inc, a day after a rally took the Dow industrials above 9,000.
* The rise in nominal value of S&P futures notwithstanding, their fair value edged lower, indicating a lack of conviction in the market's direction.
* Winding down a week loaded with quarterly reports from bellwethers in many sectors of the economy, Schlumberger Ltd, the world's largest oilfield services provider, reported a 57 percent drop in quarterly earnings, but its bottom line beat Wall Street expectations.
* Other companies reporting results on Friday include Ingersoll-Rand Co and T.Rowe Price Group Inc.
* S&P 500 futures were up 2.8 points but 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 rose 21 points and Nasdaq 100 futures gained 2 points.
* Economic data on tap includes the Reuters/University of Michigan consumer sentiment index for July due at 9:55 a.m. (1355 GMT).
* After Thursday's closing bell, Microsoft posted a steeper than expected 17 percent drop in quarterly revenue. Its shares tumbled 7 percent to $23.75 in premarket trade.
* Amazon.com fell 6.7 percent to $87.54 premarket after the company reported revenues that missed analyst estimates.
* American Express Co reported quarterly earnings that were in line with expectations.
* U.S. stocks surged Thursday, driving the Dow industrials above the key 9,000 mark for the first time since January, as strong corporate profits and rebounding home sales spurred optimism about the economy.