BANGKOK — Major indexes are off to a mixed start on Wall Street as gains for banks and industrial companies are offset by losses in Big Tech stocks like Apple and Amazon. The S&P 500 was down 0.2% in the first few minutes of trading Wednesday, a day after it narrowly managed to break a five-day losing streak. The Dow Jones Industrial Average and the tech-heavy Nasdaq also fell. Small-company stocks bucked the downward trend and rose. Treasury yields continued to climb. The yield on the 10-year Treasury note rose to 1.42%, the highest level in just over a year.