NEW YORK (MarketWatch) -- Gold futures fell slightly in electronic trading after the Federal Reserve kept its key interest rate unchanged. Gold for December delivery lost $1.90, or 0.2%, to $778.60 an ounce in electronic trading after floor trading closed. The dollar extended gains, with the dollar index up more than 1%, after the Fed kept the fed fund rate at 2%. A rising dollar tends to push down gold prices. "Just a few months ago the wide spread belief was the Fed was going to be raising rates, but their latest statement clearly suggests that will not be the case," said Peter Grandich, author of precious metals newsletter Grandich Letter. "This past thought has helped the U.S. Dollar and put pressure on gold."