Market may be more vulnerable to tightening than realised

The US economy may not be as robust as the Federal Reserve thinks.

Bianco Research President James Bianco told CNBC on Friday that most economists mistakenly believe that leading indicators are signaling an "A+" economy that can withstand rising interest rates.

Bianco said social media is creating a bandwagon effect among survey respondents that is distorting the view of the economy.

"It's more like a B- economy," he said. "It's not this screaming home run that everybody thinks it is based on the survey data."

That could mean that Fed monetary tightening could derail the stock bull market.