Credit institutions accounted for more than 63% of the value and property firms for almost 29%, it said in a recent report.
The average term of these bonds is 3.78 years and the coupon rate is 7.41%, it noted. Secured bonds accounted for 14.5% of them.
In the same period around VND59.8 trillion worth of bonds were redeemed, a 39% decline from a year ago.
Credit rating agency VIS Ratings had earlier expected around 30% of the bonds due for redemption in June to be defaulted.
Many issuers are negotiating with bondholders for a rollover. Stock brokerage VNDirect said VND144 trillion worth of bonds had been rolled over as of May.
Some companies opted to repay the bonds with other assets such as properties, it added.
In the remainder of the year nearly VND140 trillion worth of bonds are due for redemption, according to statistics from the Vietnam Bond Market Association.