Shares of Eni SpA (E) tumbled 5.19% in after-hours trading on Wednesday, following reports that the Italian energy giant is in discussions to sell a stake in its Plenitude unit.

According to sources cited by Bloomberg News, Eni is gathering bids for a 15% stake in Plenitude, with potential valuations being discussed of up to 13 billion euros ($14.13 billion). The company has reportedly received initial expressions of interest from potential buyers, although Eni has not officially confirmed these reports.

The sharp decline in Eni's stock price suggests that investors may be concerned about the implications of such a sale. While divesting a minority stake could provide Eni with additional capital, some market participants may view the potential transaction as undervaluing Plenitude or signaling a shift in Eni's long-term strategy for the unit.

Plenitude is Eni's integrated renewables and retail energy business, which has been a focus of the company's efforts to transition towards cleaner energy sources. The unit's valuation and Eni's plans for its future have been subjects of interest for investors and analysts alike.

As of now, Eni has not publicly commented on the reported stake sale discussions. Investors will likely be watching closely for any official statements from the company regarding Plenitude's future and the potential impact on Eni's overall business strategy.