SRL for [mushroomed]: Junk bonds , which [mushroomed] from less than $ 2 billion at the start of this decade , have been declining for months as issuer after issuer sank beneath the weight of hefty interest payments .
ARG-1: Junk bonds | R-ARG-1: which | ARG-3: from less than $ 2 billion | C-ARG-3: at the start of this decade