T-Mobile US stock rose about 3% Wednesday afternoon, as investors digested a report that activist investor Elliott Investment Management is pushing Deutsche Telekom to abandon a potential merger with T-Mobile US.

Elliott has built a sizable stake in Deutsche Telekom and wants the German telecom company to pursue other ways of boosting shareholder value, such as larger share buybacks, according to a Bloomberg report citing people familiar with the matter.

Deutsche Telekom already owns a little more than half of T-Mobile. The company has been considering a deal that would put both Deutsche Telekom and T-Mobile under a new parent company owned by their existing shareholders. If completed, it would be the largest public-company merger ever.

The exact size of Elliott's Deutsche Telekom stake isn't known.

Both stocks have struggled over the past year. Deutsche Telekom shares are down about 9%, while T-Mobile has fallen nearly 27%.