Complex sentence: Bumar Ltd became the main shareholder of Ursus Company, leading to Ursus becoming part of Bumar Industrial Group, which is marketing Ursus products both on foreign and domestic markets.
Split into simpler sentences: Bumar Ltd became the main shareholder of Ursus Company. That is why Ursus joined Bumar Industrial Group dealing with Ursus products both on foreign and domestic markets.