At the end of Wednesday, the total market value of all the companies that make up the S&P 500 was roughly $24.3 trillion. By close Friday, those companies had lost $1.1 trillion in market value.

The feared trade war reaction from China is expected to affect $60 billion dollars in goods. Even if those exports were banned completely, that's 18 1/2 years of exports' worth of value destroyed in two days.

Yes, China is not the only country involved (poor Norway), but the S&P 500 is not economy either. And, yes, there are multiplier effects,  but I think the market may have over-reacted this week.