Complex sentence: Their stock debuted at US $12 per share, and reached a high in excess of US $70 in early 2000, before being hit by the "tech wreck" in 2000.
Split into simpler sentences: Their stock debuted at US $12 per share, and reached a high in excess of US $70 in early 2000. The company was hit by the "tech wreck" in 2000.