KKR has made a roughly $9 billion takeover offer for Pennsylvania-based natural-gas and electricity distributor UGI, according to people familiar with the matter. The private-equity firm offered $42.50 a share for the company.

UGI shares closed at $35.09 Monday, giving the company a market value of around $7.5 billion. It couldn't be learned if UGI will be receptive, and there are no guarantees of a sale to KKR or any other buyer, the people said.

The surge in demand for steady, reliable electricity from artificial-intelligence data centers has made natural-gas power producers an attractive target after years of investor neglect. Natural-gas company Calpine, which private-equity firm Energy Capital Partners sold to Constellation Energy earlier this year, is set to become the most profitable private-equity deal of all time.