Complex sentence: In 1970 NEPCO merged with the Great Northern Paper Company, forming Great Northern Nekoosa Corporation, or GNN, which was purchased in a hostile takeover by Georgia-Pacific in 1990.
Split into simpler sentences: In 1970 NEPCO merged with the Great Northern Paper Company forming Great Northern Nekoosa Corporation or GNN. GNN was purchased in a hostile takeover by Georgia-Pacific in 1990.