Facebook is leading the fast-growing market of "social commerce" that is expected to be worth some $36 billion in the United States this year, a research firm said Wednesday.

A report by market tracker eMarketer estimated some 56 million US residents would be making at least one purchase on Facebook this year, giving the social media giant a 22.3 percent share.

Another 32 million people will have bought something on Facebook-owned Instagram, giving it a 12.9 percent share, according to eMarketer's forecast of social commerce.

The number three player is Pinterest, with a forecasted 13.9 million buyers, or 5.6 percent of the market, the report said.

According to eMarketer, US social commerce sales will rise by 35.8 percent to $36.62 billion this year, a slip deceleration from the pandemic-fueled 39 percent growth pace in 2020.

Overall, some 90 million Americans will be using social commerce, which could reach around five percent of US retail sales by 2024, according to the group.

The report is based on direct sales of products or services, or through links to retailers from social platforms, including Facebook, Instagram, Pinterest, TikTok, WeChat and others.

It excludes travel and event tickets, tips and gifts, money transfers, gambling and food services.

Despite the strong growth, the United States lags behind China, which has been a leader in social commerce and is expected to have some 424 million people making purchases on its platforms such as WeChat this year.

"US marketers can look to China as a roadmap for social commerce's development, as many of the trends that will drive its growth, like livestream shopping, originated in China," said eMarketer senior analyst Jasmine Enberg. 

"Keep in mind, however, that it's not an apples-to-apples comparison," she added.

"The social and e-commerce landscapes in the US are far more fragmented than those in China, and consumer behavior and attitudes toward digital shopping, social media consumption, online privacy and payments are different as well."