* July existing home sales expected to fall from June
* Indexes in Europe, Japan hit multi-month lows
* Dell preparing to sweeten bid for 3PAR: Bloomberg
* Dow, S&P down 0.4 pct, Nasdaq down 0.9 pct
* For up-to-the-minute market news see
By Ryan Vlastelica
NEW YORK, Aug 24 (Reuters) - U.S. stock index futures were lower on Tuesday and tracked global equities as investors prepared for data expected to show further weakness in the U.S. housing market.
* July existing home sales is scheduled to be released at 10 a.m.(1400 GMT). Wall Street expects sales at an annualized rate of 4.7 million, according to Thomson Reuters data, a decline from the 5.37 million units posted in June. Improvement in the housing market is seen as key for economic recovery.
* European stocks tumbled to a 5-week low in morning trading, with construction shares among the leading decliners. In Tokyo, shares sank to a 15-month closing low with hedge funds and foreigners seen selling amid mounting concern about the authorities' inaction over the strong yen, which threatens a fragile economic recovery.
* Dell Inc is preparing to sweeten its bid for 3PAR Inc, according to a Bloomberg report. The move comes a day after Hewlett-Packard Co bid $1.6 billion for the data storage company.
* S&P 500 futures fell 8.7 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 lost 70 points, and Nasdaq 100 futures slid 13.25 points.
* On Monday, U.S. stocks slipped in one of the lightest volume sessions of the year, erasing earlier gains that were sparked by HP's bid for 3PAR. Merger and acquisition activity is often considered a positive sign for the economy.
* Medical device maker Medtronic Inc is scheduled to report results on Tuesday. It is the only S&P 500 company due to report earnings on Tuesday, apart from discount retailer Big Lots Inc, which posted second-quarter earnings that beat expectations by a penny; the discounter also raised its 2010 profit view for the second time.
* October crude futures were on track to fall for a fifth day, dropping 1.2 percent to $72.20 per barrel on concerns about the ability of the U.S. to work through its record inventory.
* Nokia Corp and chipmaker Intel Corp said on Tuesday their joint software venture, seen as crucial in helping Nokia improve its position at the top end of the handset market, had got off to a solid start. ( Editing by W Simon )