Why call a top? First off, Dow means nothing but if we are talking it, it tests 13k a couple times before breaking through it. S&P means much more, the dow is what the 6 o'clock news will talk about.
Yes, I have heard this parity argument before. You do realize that there are other ways to reach parity? 1: Go long on both. If the lower priced one is increasing at a faster rate, they will eventually reach parity. 2. Go short on both. If the higher priced one is decreasing at a faster rate, they will eventually reach parity. 3. Massive asteroid collides with earth. They'll both reach zero pretty quickly. etc.