Credit investment and private equity firm Ares Management LLC is building a blocking stake in Boart Longyear , sources told Street Talk on Tuesday.

The embattled mining services company has two classes of bonds outstanding in the United States junk bond market – a $US300 million ($319 million) secured bonds paying 7 per cent and maturing in 2018, and $US300 million of unsecured bonds maturing in 2021. The secured bonds, which pay a hefty 10 per cent coupon, are trading at 5 per cent above face value while the lower-ranking unsecured bonds are lingering at 75¢ in the dollar.