NEW YORK - Wall Street’s main indexes closed sharply lower on Thursday, marking their deepest one-day declines since June as investors dumped the high-flying technology sector, while economic data highlighted concerns about a long and difficult recovery. The Nasdaq led the pullback with a decline of almost 5% a day after it and the S&P 500 posted record closing highs. The Nasdaq’s biggest drags came from heavyweights Apple Inc ( AAPL.O ), Microsoft Inc ( MSFT.O ), Amazon.com Inc ( AMZN.O ), Tesla Inc ( TSLA.O ) and Nvidia Corp ( NVDA.O ). The S&P tech sector .SPLRCT and the Philadelphia chip index .SOX both fell almost 6% on the day. Markets had soared from March lows, powered by fiscal and monetary support hopes for a swift economic recovery. But some participants said investors had become too optimistic. “Think about the mounting number of risks the market has been shrugging off over the last couple of months here,” said Emily Roland, co-chief investment strategist at John