CCB bought 495 shares of CEZ Electro in a deal registered with the central depository on November 29, the company said in a bourse filing.
No financial details of the deal were disclosed.
CEZ Electro, a unit of Czech power utility CEZ, said earlier this week that Bulgaria's UniCredit Bulbank had sold out its minority stake of 495 shares in the company for an undisclosed sum.
CEZ Electro supplies electricity to over 1.9 million customers in the Sofia region and parts of western and northern Bulgaria.
CCB was Bulgaria's ninth largest bank in terms of assets at the end of October, according to data from the country's central bank. Bulgaria has 24 domestically-registered banks and branches of seven foreign-based lenders.
(1 euro=1.95583 Bulgarian levs)