Complex sentence: Zayat continued to run Al Ahram until 2007, but periodically returned to the United States, where he started buying racehorses and formed Zayat Stables in 2005.
Split into simpler sentences: Zayat continued to run Al Ahram until 2007. He periodically returned to the United States, where he started buying racehorses and formed Zayat Stables in 2005.