Complex sentence: The United Fruit Company had been formed in 1899 by the merger of two large American corporations, that together had major holdings of land and railroads across central America, which it used to support its business of exporting bananas.
Split into simpler sentences: The United Fruit Company had been formed in 1899 by the merger of two large American corporations. The new company had major holdings of land and railroads across central America, which it used to support its business of exporting bananas.