NEW YORK, United States — Retail stocks rebounded on Wednesday amid signs of strong consumer spending during the holiday season, sending a key benchmark up the most in eight years.

The S&P 500 Retailing Index climbed 5.6 percent, reaching its session high in the final hour of trading, and seeing its biggest one-day gain since the spring of 2010. That came after Amazon posted record holiday spending and Mastercard said department stores’ online sales were up more than 10 percent from last year. Among the biggest gainers, aside from Amazon, which added 7.5 percent, were Kohl’s, which gained as much as 8.7 percent, and Dollar General, which rose 6 percent.

The broader S&P 500 Consumer Discretionary Index surged as much as 4.6 percent, making it the best performing among 11 main groups in the wider benchmark index.

The worst month for US stocks since the financial crisis had raised concerns about consumer spending in the most important season of the year for retailers. As of Christmas eve, for example, the consumer discretionary group had fallen 15.2 percent in December, a touch more than the broader market.

By Jeran Wittenstein; editor: Catherine Larkin, Scott Schnipper