US STOCKS-Wall St's gains fade as Yellen questions economy's resilience
* Indexes post losses for week
* Yellen lays out concern economic potential is slipping
* Twitter shares down after Salesforce CEO rules out bid
* Indexes up: Dow 0.2 pct, S&P 0.02 pct, Nasdaq 0.02 pct (Updates to close)
By Caroline Valetkevitch
Oct 14 (Reuters) - U.S. stocks ended little changed on Friday, losing ground late after Federal Reserve Chair Janet Yellen's comments on the economy unnerved investors.
Financial shares finished up, giving the S&P 500 its biggest boost after stronger-than-expected bank results, but gave up most of their early gains. Healthcare shares led declines.
Yellen, in a speech at a conference of policymakers and academics, laid out the deepening concern at the Fed that U.S. economic potential is slipping - and may need aggressive steps to rebuild it.
"In looking at the market, I think, yes, (Yellen's speech) had a dovish tilt to it if you took it literally," said Quincy Krosby, market strategist at Prudential Financial in Newark, New Jersey. Continuación...