By Stephen Culp NEW YORK (Reuters) – Wall Street ended the session lower on Thursday, crossing the finish line of a grim month and quarter, a dismal coda to the S&P 500’s worst first half in more than half a century. All three major U.S. stock indexes finished the month and the second quarter in negative territory, with the S&P 500 notching its steepest first-half percentage drop since 1970. The Nasdaq had its largest-ever January-June percentage drop, while the Dow suffered its biggest first-half percentage plunge since 1962. All three indexes posted their second straight quarterly declines. …