The Globe and Mail reports in its Wednesday edition that U.S. and Canadian stocks slumped on Tuesday, at the start of one of the market's historically worst months. A Reuters dispatch to The Globe reports that all three U.S. major indexes and the S&P/TSX Composite Index recorded their biggest daily percentage declines since early August. The CBOE Volatility Index, Wall Street's fear gauge that measures market expectations of stock market swings, jumped 33.2 per cent to 20.72, the biggest daily percentage gain and highest close since early August. Market sentiment weakened as Institute for Supply Management data on Tuesday showed U.S. manufacturing remained subdued despite a modest improvement in August from an eight-month low in July. Alexis Investment Partners president Jason Brown says, "Everybody is reporting about how September is such a horrible month and that tends to feed on itself." The so-called Magnificent Seven mega-cap technology stocks, which have led this year's rally, slumped. Nvidia dropped nearly 10 per cent. Alphabet fell 3.6 per cent, Apple lost 2.7 per cent and Microsoft shed 1.8 per cent. Traders are awaiting several U.S. labour market reports ahead of Friday's non-farm payrolls data for August.