This list of 'junk' companies keeps getting longer

A 'junky' bond market

The bottom of the corporate debt barrel is getting more crowded.

The worst of the worst when it comes to bond issuance, or those Moody's Investors Service rates as "B3 negative" and lower, saw their rolls swell to a five-year high in June, the ratings agency said this week.

For the first time since July 2010, that group of at-risk issuers numbered more than 200. The 206 companies represented a 12 percent gain just over the previous quarter and a 24 percent surge from a year ago.

In plain terms, the gains in the list mean credit quality is worsening. But that only tells part of the story.