The new design does away with the strictly vertical timeline that has been Twitter's signature look, offering instead a greater focus on photos and content cards, the Washington Post reported Wednesday.
The tweaks are apparently aimed at making Twitter more accessible to new users who may feel overwhelmed by the mass of content pouring in to the site.
It's also likely a response Twitter's first earnings report as a public company revealed last week.
Investors hammered the stock after learning Twitter's user base isn't growing as quickly, and current users are spending less time on the site.
The redesign suggests Twitter knows it should move fast to address the problems that worried its investors, James Gellert of financial analysis firm Rapid Ratings told the Post.
"Even they recognize it's not the most intuitive and usable technology," Gellert said. A Twitter evolution, he added, "is going to take time. But they have to demonstrate that they're connecting the dots."
New features and design updates from Twitter typically go out to a small, random pool of users for some quiet testing before they're rolled out to the larger user base.