U.S. stocks ended mixed on Thursday, with the Nasdaq Composite adding 49.32 points, or 0.23%, to an unofficial 21,218.75—its highest close on record. The tech-heavy gauge outperformed as large-cap technology names extended recent gains. The broader market lagged. The S&P 500 slipped 7.56 points, or 0.12%, to an unofficial 6,337.50, while the Dow Jones Industrial Average fell 249.32 points, or 0.56%, to 43,943.80. Traders pointed to a disappointing 30-year Treasury bond auction earlier in the session, which pushed long-term yields higher and weighed on rate-sensitive sectors, muting sentiment outside of technology shares.