China’s fast-growing bond market broke new ground to start 2012, just not the kind that its proponents were hoping to break: over the past few days it has served up its first-ever triple A bond default and its first default on a special bond designed for smaller businesses.

Both were quickly resolved and creditors were repaid in full, but the defaults shone a rare light on the mounting credit risks in China that could strain its financial system in the years ahead. Defaults by Chinese companies on bonds issued abroad are not unusual. In the domestic market, they are still a new phenomenon.

“Defaults will be increasingly frequent because so much was borrowed over the past few years that has to be paid back now,” said Wang Jing, head of fixed-income research with Jinyuan Securities. The turbulence of the past week also underscored the increasing complexity of the Chinese economy, and the new dangers that this entails.