Wall St. rises after Yellen signaled improved economic performance

U.S. stock indices rose on Friday before the weekend after Fed Chair Janet Yellen pointed to the improved economic performance in the medium term, with inflation nearing the bank's targets. 

Yellen also said in the last months, chances of a rate hike rose as inflation prospects improved while the employment sector held its ground, underpinning stocks. 

On the other hand, dollar wavered considerably after Yellen's speech as she didn't signal a specific date for hiking rates, which helped shares of American exporters. 

The dollar index, which tracks the greenback against an array of six main currencies, fell to 94.67 from the opening of 94.69, with a session-low at 94.23, and a high at 95.04, after the index hit its highest this week at 94.95. 

Standard and Poor's 500 rose 0.57%, or 12.33 points to 2,184.80, while Dow Jones gained 0.48%, or 87.66 points to 18,536.07. 

Tech-heavy NASDAQ rose 0.56%, or 29.11 points to 5,241.32.