Pinterest's user base grew slightly more than nine percent to 82.4 million US users last year, topping Snapchat's 80.2 million users, according to the research firm eMarketer.

The growth spurt would make Pinterest the number three US social platform behind Facebook and its Instagram unit.

"While Snapchat has a young core audience that it caters to, Pinterest has a more universal appeal, and it's made significant gains in a wide range of age groups," said eMarketer analyst Nazmul Islam.

Shares in San Francisco-based Pinterest ended the formal trading day up about 10 percent.

The market tracking firm expected Pinterest to be more popular among US users in the years ahead, with the online bulletin board's lead on the image-centric messaging service widening through the end of 2023.

With its share offering, Pinterest got off to a flying start on Wall Street early last year in the market debut for the visual discovery service.

Pinterest, launched in 2010, is a virtual bulletin board platform, with users decorating their boards with pictures showcasing interests including food, fashion, travel and lifestyle.

It also enables users to link to online shopping and other services to find items they have "pinned."