When it comes to bond indexing, larger debt issuance does not inherently reflect higher issuer risk.
The largest issuer in the bond market is the U.S. government, which continues to be viewed as having remote default risk.
In the corporate bond market, larger companies tend to be the largest issuers. However, they also have generally had the largest asset bases and revenues to service that debt. Moreover, larger companies may be healthier on average than smaller companies.
Many of the companies held by fixed income indices are very familiar to equity investors. For example, the top weights in the widely followed corporate bond benchmark, Markit iBoxx USD Liquid Investment Grade Index, are large, blue chip companies like JP Morgan Chase, AT&T, and Verizon. In fact, a majority of the top issuers in the index are also in the top 125 holdings of the S&P 500 Index.1