(Update quotes)

By Caroline Valetkevitch

Sep 16 (.) – The S&P; 500 ended a slightly lower volatile session on Wednesday as losses in tech stocks weighed down the index even after the US Federal Reserve promised that interest rates will stay near zero for a long time.

* The index extended gains and the Dow Jones briefly rose more than 1% in afternoon trading after the Fed held rates near zero and announced it will leave them at that until inflation is on track to « moderately exceed. » your goal of 2% « for some time. »

* But the market lost ground before the close, dragged down by falling tech stocks.

* « The Fed will be very supportive of the economy and Powell wants Congress to deliver more stimulus, » said Tim Ghriskey, chief investment strategist at Inverness Counsel in New York, New York. « It is a concern that Congress is not supporting. »

* The central bank meeting is the first after a shift in its monetary policy announced last month that aims to offset years of weak inflation and allow the economy to continue creating jobs for as long as possible.

* The Dow Jones Industrial Average rose 36.78 points, or 0.13%, to 28,032 units, while the S&P; 500 fell 15.71 points, or 0.46%, to 3,385.49 units. The Nasdaq, meanwhile, lost 139.855 points, or 1.25%, to 11,050.469 units.

(Reporting by Shreyashi Sanyal and Devik Jain in Bengaluru; edited in Spanish by Rodrigo Charme)