Investing experts: Why 'just buy the market' doesn't necessarily apply to bonds

The notion of "just buy the market" is a common investment strategy, particularly for equities, where index funds or ETFs tracking a broad market index like the S&P 500 can provide diversified exposure. However, this approach may not be as straightforward for bond investors, who often rely on the Bloomberg Aggregate Bond Index as a benchmark. According to investing experts, this flagship index has some idiosyncrasies that bond investors should be aware of.

One key issue with the Bloomberg Aggregate Bond Index is its market-capitalization-weighted construction, which can lead to overexposure to certain sectors or issuers. For example, the index is heavily weighted towards US Treasury and agency securities, which can create a bias towards government debt. Additionally, the index's rules-based methodology can result in some unexpected inclusions or exclusions, such as the treatment of certain types of mortgage-backed securities. As a result, investors who simply "buy the market" through an index fund or ETF tracking the Bloomberg Aggregate Bond Index may be taking on more risk or exposure than they intend.

Bond investors should watch how these idiosyncrasies impact their portfolios and consider actively managed strategies or customized bond allocations that better align with their investment objectives. Additionally, investors should keep an eye on potential changes to the Bloomberg Aggregate Bond Index's methodology or composition, which could affect the performance of index-tracking funds. As the bond market continues to evolve, investors would do well to stay informed about the nuances of their benchmark and adjust their strategies accordingly.

Originally reported by cnbc.com. BondNews adds analysis for finance & markets readers.