U.S. companies now face the highest levels of debt on record — more than $10.5 trillion, according to the Federal Reserve and the Securities Industry and Financial Markets Association, or SIFMA. The coronavirus pandemic is only part of the story. The corporate debt market is where companies go to borrow cash. And for over a decade, super-low interest rates left over from the 2008 financial crisis have made borrowing easier and easier. Since then, U.S. companies have regularly offered up bonds for sale, taking advantage of the cheap access to cash. Sometimes companies can get reckless with debt, and this can result in bonds facing downgrades and low ratings, putting those companies at junk bond status. Overborrowing can result in companies becoming "fallen angels" or "zombie" companies. Between rising interest rates and inflation concerns, Wall Street is watching the bond market closely and checking the pulse of the U.S. economy. Here's how the corporate bond market got to these "bubble" levels and just how risky this massive amount of debt may be to the U.S. economy. » Subscribe to CNBC: https://cnb.cx/SubscribeCNBC » Subscribe to CNBC TV: https://cnb.cx/SubscribeCNBCtelevision » Subscribe to CNBC Classic: https://cnb.cx/SubscribeCNBCclassic About CNBC: From 'Wall Street' to 'Main Street' to award winning original documentaries and Reality TV series, CNBC has you covered. Experience special sneak peeks of your favorite shows, exclusive video and more. Connect with CNBC News Online Get the latest news: https://www.cnbc.com/ Follow CNBC on LinkedIn: https://cnb.cx/LinkedInCNBC Follow CNBC News on Facebook: https://cnb.cx/LikeCNBC Follow CNBC News on Twitter: https://cnb.cx/FollowCNBC Follow CNBC News on Instagram: https://cnb.cx/InstagramCNBC Subscribe to CNBC PRO: https://cnb.cx/2NLi9AN #CNBC Behind The Corporate Bond Market's $10.5 Trillion Debt 'Bubble'