NEW YORK, Dec. 22 (Xinhua) -- U.S.-listed Chinese companies traded mostly lower on Wednesday with seven of the top 10 stocks by weight in the S&P U.S. Listed China 50 index ending the day on a downbeat note.

Shares of Bilibili and Alibaba Group Holding dipped 4.68 percent and 4.2 percent, respectively, leading the laggards in the top 10 stocks in the index.

Shares of XPeng and JD.com climbed 4.5 percent and 0.46 percent, respectively, leading the advancers in the top 10 stocks.

U.S. stocks extended gains on Wednesday, following an upbeat prior session, as worries over the Omicron variant moderated.

The Dow Jones Industrial Average increased 261.19 points, or 0.74 percent, to 35,753.89. The S&P 500 rose 47.33 points, or 1.02 percent, to 4,696.56. The Nasdaq Composite Index advanced 180.81 points, or 1.18 percent, to 15,521.89.

The Cboe Volatility Index, widely considered as the best fear gauge in the stock market, dropped 11.33 percent to 18.63.

As of Tuesday, the S&P U.S. Listed China 50 index, which is designed to track the performance of the 50 largest Chinese companies listed on U.S. exchanges by total market cap, stood at 2,953.70, marking a 12.27-percent loss for the month-to-date returns and a 43.47-percent slide for the year-to-date returns.