S&P 500 valuation gauge challenges Internet-bubble highs

 U.S. stocks have “no room for error” after rising for more than a decade, according to Peter Boockvar, chief investment officer at Bleakley Advisory Group LLC. Boockvar cited the ratio between the S&P 500 Index’s enterprise value, reflecting debt and cash levels along with market value, and Ebitda -- earnings before interest, taxes, depreciation and amortization -- in an email Monday. The ratio spent multiple days above 14 last month for the first time since 2000, when an Internet-driven bubble in stocks burst, according to data compiled by Bloomberg. Tuesday’s reading was 14.1.