Sarah Tew/CNET

At least three U.S. carriers have started issuing software updates for the Samsung Galaxy S4, according to a number of reports.

Verizon, AT&T, and Sprint are currently in the process of pushing out a rather large update to the flagship smartphone. While none of these carriers has made a formal announcement, each report mentions the same basic features.

Key among the changes packaged in the 357MB file is the ability to move apps from the handset to an external microSD card. Commonly known as "apps to SD," this capability frees up the smartphone's internal storage, potentially improving the handset's performance.

Changes are said to also include Samsung Knox security software and a new locked bootloader, something that could potentially anger rooted users. Rounding out the changes are status bar transparency options and legibility settings, in addition to other general software enhancements.

It is interesting that all three carriers are pushing out the update at the same time; perhaps Samsung has garnered enough Android clout to get them lined up? As of now there are no reports of an update for T-Mobile's version of the Galaxy S4.

Those of you with a Samsung Galaxy S4 are encouraged to keep an eye on your status bar for a notification. Both Sprint and AT&T are reportedly issuing an over-the-air update while Verizon is employing desktop software via Samsung Kies.