US STOCKS-Wall St turns negative as IMF warns on Greece
* IMF warns Greece needs debt extension
* June nonfarm payrolls increase less than expected
* Average hourly earnings unchanged
* Six of the 10 S&P sectors down
* Indexes down: Dow 0.12 pct, S&P 0.09 pct, Nasdaq 0.27 pct (Changes quote, updates prices)
By Sweta Singh
July 2 (Reuters) - U.S. stocks turned negative after the International Monetary Fund warned Greece may need a further large debt writeoff, and weak U.S. jobs data dampened the economic outlook.
Six of the 10 major S&P sectors were in the red by midday, after opening positive.
IMF's warning comes as Greece readies for a Sunday referendum on an international bailout deal that Prime Minister Alexis Tsipras has urged voters to reject. Continuación...