The Tribune

By Kelley Cotter, 

Penn State

President Donald Trump announced on September 19, 2025, a preliminary agreement for the sale of a majority stake in TikTok from Chinese tech giant ByteDance to a group of US investors following Trump’s negotiation with Chinese leader Xi Jinping.

The deal would create a new US-only version of the app, bringing it into compliance with a law signed by former President Joe Biden on April 23, 2024, and upheld by the Supreme Court on January 17, 2025. Specifics of the deal remain to be hammered out, and left unresolved is the fate of the video sharing app’s core algorithm.

The Chinese government has indicated it will not permit ByteDance to sell the algorithm, because it is classified as a controlled technology export, per Chinese law. Meanwhile, US tech industry executives and some lawmakers say compliance with the law requires the algorithm to be under American control. The deal as proposed includes licensing the algorithm so that it remains Chinese intellectual property while the US version of the app continues to use the technology.

TikTok’s For You Page algorithm is widely considered the most important part of the app. As one analyst put it: “Buying TikTok without the algorithm would be like buying a Ferrari without the engine.”

How the TikTok
algorithm works

In some ways, the TikTok algorithm does not differ significantly from other social media algorithms. At their core, algorithms are merely a series of steps used to accomplish a specific goal. They perform mathematical computations to optimise output in service of that goal.

There are two layers to the TikTok algorithm. First, there is the abstract layer that defines the outcome developers wish to accomplish. An internal document shared with The New York Times specified that TikTok’s algorithm optimises for four goals: “user value,” “long-term user value,” “creator value” and “platform value”.

But how do you turn these goals into math? What does an abstract concept like “user value” even mean? It’s not practical to ask users whether they value their experience every time they visit the site. Instead, TikTok relies on proxy signals that translate abstract outcomes into quantifiable measures — specifically, likes, comments, shares, follows, time spent on a given video and other user behavior data. These signals then become part of an equation to predict two key concrete outcomes: “retention,” or the likelihood that a user will return to the site, and “time spent” on the app.

The TikTok For You Page algorithm relies on machine learning for predicting retention and time spent. Machine learning is a computational process in which an algorithm learns patterns in a dataset, with little or no human guidance, to produce the best equation to predict an outcome. Through learning patterns, the algorithm determines how much individual data signals matter for coming up with a precise prediction.

What’s likely to change for US users

The sale has not been finalised, and what happens to the algorithm is unresolved. However, it’s fairly certain that TikTok will change. I see two key reasons for change.

First, the proposed app’s US-only user population will alter the makeup of the underlying dataset informing algorithmic recommendations on an ongoing basis.

Second, it’s possible that the majority share owners of the new app will decide to adjust the algorithm, particularly when it comes to content moderation. The new owners may wish to modify TikTok’s Community Guidelines.

The bottom line is algorithms are highly sensitive to context. They reflect the interest, values and worldviews of the people who build them, the preferences and behaviours of people whose data informs their models and the legal and economic contexts they operate within.

This means that while it’s difficult to predict exactly what a US-only TikTok will be like, it’s safe to assume it will not be a perfect mirror image of the current app.

• Originally published on www.theconversation.com.