The Nasdaq 100 index posted its fourth consecutive session in the green on Thursday, closing up 0.6% at 19,576 points and reaching new all-time highs as tech stocks drive broader market gains. The S&P 500 also recorded its fourth straight positive day, rising 0.2% to a record closing level of 5,433 points, rebounding from a morning dip caused by disappointing unemployment claims data. In the afternoon, traders regained confidence in risky assets after U.S. Treasury Secretary Janet Yellen express