According to S&P's Global Fixed Income Research team, $8.3 trillion in S&P rated global corporate debt matures through year-end 2017, with $1.9 trillion maturing in 2014. Of this $1.9 trillion, $178 billion is U.S. nonfinancial speculative debt ($41 billion in Europe). They break out the debt maturities by region, rating and sector in the video.
Source: Standard & Poor's (CreditMatters TV)
Here's a chart of the U.S. high yield corporate bond ETF $HYG. Is the recent sell-off due to interest rate risk? Or is there a worry about credit risk and refinancing risk going forward. According to iShares.com (as of 6/5/2013), HYG has 25.62% of its holdings maturing in 1-5 years and 69.9% maturing in 5-10 years. HYG has a 'weighted average maturity' of 4.69 years and an 'effective duration' of 4.19.