"The sharp drop in FB market cap today and the accompanying drag on the S&P500 index is ... a stark reminder of the high concentration of mega-cap Tech stocks in the S&P 500 — and the vulnerabilities that such concentration brings," Goldman Sachs' Chris Hussey said in a note Thursday.Investors also eyed economic data. U.S. joblessThe focus now turns to the
set for release Friday morning. Economists surveyed by Dow Jones expect a gain of 150,000 jobs, but some losses as large as 400,000.