The issuances totaled over VND60 trillion (US$2.55 billion), down 50% from the second quarter. Almost all were private placements.
Real estate accounted for VND8 trillion, and banks for VND48.6 trillion.
State lenders BIDV and VietinBank issued bonds worth VND6.867 trillion and VND4.21 trillion.
Private bank OCB accounted for VND6.6 trillion.
Bank bonds fell by nearly 38% in value year-on-year.
According to VNDirect Securities, the primary bond market started to cool down in March as investors awaited a new decree that sought to protect them and improve the quality of the capital market.
In the first nine months of the year issuances were down 43% to VND248.6 trillion, with banks and financial companies accounting for 58% and real estate firms for 21.5%.
The five biggest issuers were three banks and two private conglomerates.
Vietcombank Securities said the bond market would continue to cool down amid falling liquidity.
Higher interest rates offered on bank deposits are luring away investors, it added.