Mainfreight surged $5.25 or 8.24% to a near seven-month high of $69. (Image: Getty)The New Zealand sharemarket had its biggest single-day fall in nearly six weeks despite an increase in business confidence, but was weighed down by a meltdown on Wall Street.The S&P/NZX 50 Index was on a gradual slide from the opening and closed at 13,762.78, declining 213.89 points or 1.53%. The index’s previous worst fall was 1.64% on May 20.There were 100 decliners and 43 gainers on the main board, with turnover reaching 29.5 million shares worth $129.8m.A strong local business outlookGreg Smith, investment specialist with Generate...