Five years to the day after the peak of the last global investment bubble, signs that another one may be about to burst could be seen, ironically enough, in the telecommunications industry.

Last Wednesday, two private equity firms suffered a setback in their attempt to fund the acquisition of Telcordia, a US supplier of network software, by issuing junk debt. As jittery bond markets caused a sudden spike in long-term interest rates, Telcordia's banks took the unusual step of postponing the completion of its bond issue. A day later, on the anniversary of the 2000 Nasdaq peak, Moody's Investors Service revised its outlook for the technology company, warning the bonds could fall to a rating indicating a substantial risk of default.