Complex sentence: Following the acquisition, Mattel experienced dismal results were exacerbated by $105 million USD loss where management had projected a US $50-million profit and later Mattel's stock crashed, wiping out US $3 billion of shareholder value in a single day.
Split into simpler sentences: Following the acquisition, Mattel experienced a USD $105 million loss where management had projected a US $50-million profit. This caused Mattel's stock to crash, wiping out USD $3 billion of shareholder value in a single day.