US STOCKS-Futures flat after mixed data overseas

(Corrects to show Markit flash U.S. PMI to be released at 9:45 a.m. EDT, not 9:00 a.m.)

* Flash PMI, existing home sales data due

* Wisconsin Energy (NYSE: WEC - news) to buy Integrys for $9.1 bln

* Futures: Dow off 4 pts, S&P up 0.25 pt, Nasdaq off 2.25

By Chuck Mikolajczak

NEW YORK, June 23 (Reuters) - U.S. stock index futures were 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, topping the 49.7 and edging above the 50-point level that separates growth in activity from contraction for the first time since December.

* 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 showing contraction.

* The S&P 500 has risen for six straight sessions, its longest streak since mid-April, to gain 1.7 percent over that span.

* Markit's flash PMI reading for the U.S. for June is due out at 9:45 a.m. EDT (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 0.25 point and fair value - a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract - indicated a flat open. Dow Jones industrial average e-mini futures fell 4 points and Nasdaq 100 e-mini futures lost 2.25 points.

* France won an option to buy 20 percent of Alstom (TLO: ALSO.TI - news) from construction group Bouygues (Other OTC: BOUYF - news) on Sunday in an eleventh-hour deal, clearing the way for the agreed sale of Alstom (Paris: FR0010220475 - news) 's energy business to General Electric (Swiss: GE.SW - news) .

* Wisconsin Energy said it would buy Integrys Energy (NYSE: IEH - news) 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 16.3 percent to $70.90 in light premarket trading.

* European stocks dipped on the downbeat readings of euro zone business while Asian stocks rose on encouraging data from China's factory sector. (Editing by Bernadette Baum)