(Corrects fifth paragraph to show that Markit flash U.S. PMI data is due out at 9:45 a.m. EDT, not 9:00 a.m.)
* Flash PMI, existing home sales data due
* Wisconsin Energy to buy Integrys for $9.1 bln
* Oracle to buy Micros for $68 per share
* Futures: Dow off 4 pts, S&P up 0.75 pt, Nasdaq off 1.25 pts
By Chuck Mikolajczak
NEW YORK, June 23 (Reuters) - U.S. stocks were set to open little changed on Monday after a six-day rally in the benchmark S&P 500, as upbeat manufacturing data in China was offset by soft readings on business activity in Europe.
* The HSBC/Markit Flash China Manufacturing Purchasing Managers' Index rose to 50.8 in June from May's final reading of 49.4, beating a Reuters poll forecast of 49.7 and creeping above the 50-point level that separates growth in activity from contraction. It was the first time in six months that activity in China's factory sector had expanded, thanks to a surge in new orders.
* But Markit's Composite Purchasing Managers' Index (PMI) for the euro zone fell to 52.8 from May's 53.5, well below the estimate for 53.5 in a Reuters survey, with France being a notable laggard and showing contraction.
* The S&P 500 has risen for six straight sessions, gaining 1.7 percent over that span in its longest streak of advances since mid-April.
* Markit's flash PMI reading for the U.S. for June is due at 9:45 a.m. (1345 GMT). Expectations call for a reading of 56.5 for the month, just above the prior 56.4.
* Later in the session at 10:00 a.m. (1400 GMT). Existing home sales data for May is due, with expectations for a rise to an annual rate of 4.73 million units from 4.65 million in April.
* S&P 500 e-mini futures were up 0.75 point and indicated a flat open against 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 e-mini futures fell 4 points and Nasdaq 100 e-mini futures lost 1.25 points.
* France won an option to buy 20 percent of Alstom from construction group Bouygues on Sunday in an eleventh-hour deal, clearing the way for the agreed sale of Alstom's energy business to General Electric.
* Oracle Corp said it would buy Micros Systems in a $5.3 billion deal to expand its offerings in the hospitality and retail industries. Micros shares rose 3 percent to $67.75 before the opening bell. Oracle shares were up 0.5 percent.
* Wisconsin Energy said it would buy Integrys Energy Group Inc in a deal valued at $9.1 billion to create a larger, more diverse Midwest electric and natural gas delivery company. Integrys shares were up 11.2 percent to $67.80 in premarket trading.
* Harbinger Group Inc, the holding company for Spectrum Brands, said it had offered to buy retailer Central Garden & Pet Co for $10 per share, or acquire its pet business for $750 million. Central Garden shares were up 6 percent to $9.80 in premarket trading. (Editing by Bernadette Baum)