Complex sentence: Disagreements between Standard and Ferguson culminated in Standard breaking all connections with both Ferguson and tractor production in the summer of 1959 by which time Harry Ferguson Ltd had sold out to Massey Harris, to become Massey-Harris-Ferguson and then Massey Ferguson.
Split into simpler sentences: Disagreements between Standard and Ferguson culminated in Standard breaking all connections with both Ferguson and tractor production in the summer of 1959. By this time Harry Ferguson Ltd had formed a merger with Massey Harris to become Massey-Harris-Ferguson, later shortened to Massey Ferguson.