US STOCKS-Wall St to open flat, quarter set to end positive
* S&P 500, Nasdaq to add to string of quarterly gains
* Chicago PMI, pending home sales data due
* MannKind rallies on approval of inhaled insulin
* Futures: Dow off 5 pts, S&P flat, Nasdaq up 2 pts (Updates prices)
By Rodrigo Campos
NEW YORK, June 30 (Reuters) - U.S. stocks were set to open little changed on Monday ahead of business activity and home sales data, with the S&P 500 and Nasdaq Composite indexes set to close a sixth straight quarter of gains - a streak not seen in more than 14 years.
* The Chicago Purchasing Manager Index is due to be released at 9:45 a.m. EDT (1345 GMT) and the National Association of Realtors will publish its pending home sales index at 10:00 a.m. (1400 GMT).
* With an abbreviated week due to the U.S. Independence Day holiday on Friday and a ream of data due Wednesday and Thursday, there may be increased volatility in a market that has been frustratingly placid for some traders.
* The S&P closed Friday 0.1 percent below its record close set a week earlier. Continuación...