Based on the responses of 7,200 US teens with an average age of 16, the latest "Taking Stock With Teens" results from Piper Jaffray, the investment bank, found about three-quarters (76%) now use Instagram, up from 69% in its previous report.
Facebook, once the most popular site, has witnessed a significant fall in popularity from 72% to 45% and has been overtaken by Twitter, Marketing Charts reported.
Twitter is now the second most popular social media site, used by 59% of US teenagers, although this too is a decline on its 63% usage recorded six months ago.
Pinterest and Tumblr are used by 22% and 21% respectively while 14% use "other" social media sites, including Snapchat (4%).
Of particular note for marketers, the report found 38% of US teenagers believe Instagram is a favourable marketing channel to reach them, a view shared by 34% about Twitter and 21% about Facebook.
"Teens use social media, mainly Instagram, to create their own unique personal brands and seek peer affirmation," explained Steph Wissink, co-director of research at Piper Jaffray.
Amazon is by far their preferred shopping website (32%), followed by Nike (8%), eBay (5%) and Forever 21 (5%) while 2% each opt for Urban Outfitters, Victoria's Secret, American Eagle, Nordstrom, Pacsun, Brandy Melville and Eastbay.
Apple remains the top consumer electronics brand for teens. In all, 67% own an iPhone, up 6% from spring 2014, and almost three-quarters (73%) expect their next phone to be an iPhone.
Over half (54%) own an iPad, 12% have an iPad Mini, while 16% own an Android tablet, 6% own a Kindle Fire, and 7% have a smartwatch.
In other findings, food is their second largest spending category (20%), behind clothing (21%) and ahead of accessories/personal care (10%).
The average spend on fashion goods per year has risen to $1,069, up from $995 annual spend recorded in the same period last year, and Nike is the top preferred clothing brand for almost a quarter (22%), followed by American Eagle (8%) and Forever 21 (7%).
Data sourced from Piper Jaffray, Marketing Charts; additional content by Warc staff