Two-plus years of a near-unbroken rally and a market may perhaps be forgiven for a pullback — unless that market is in China, where the sharpest monthly jump in bond yields since the rally began has prompted worries another mainland boom looks to be on borrowed time.

Concerns about a rise in defaults, excess leverage and doubts about the likelihood of more monetary easing has sapped investor appetite and overshadowed China’s massive bond market.

A series of defaults and near-defaults by state-owned enterprises (SOE) have dominated attention since SOE’s government backing had, until now, been considered a guarantee of prompt and full payment. Last month. two SOEs missed scheduled bond payments, while a third suspended trading of its notes and warned it would struggle to make a payment due this month.